Adaptive Current Regulation for Solid State Lighting

ABSTRACT

Representative embodiments provide an apparatus, system, and method for power conversion to provide power to solid state lighting, and which may be coupled to a first switch, such as a dimmer switch. A representative system for power conversion comprises: a switching power supply comprising a second, power switch; solid state lighting coupled to the switching power supply; a voltage sensor; a current sensor; a memory; a first adaptive interface circuit to provide a resistive impedance to the first switch and conduct current from the first switch in a default mode; a second adaptive interface circuit to create a resonant process when the first switch turns on; and a controller to modulate the second adaptive interface circuit when the first switch turns on to provide a current path during the resonant process of the switching power supply.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/639,255, filed Dec. 16, 2009, which is a continuation-in-part of U.S.patent application Ser. No. 11/655,558, filed Jan. 19, 2007 (now U.S.Pat. No. 7,656,103), which claims the benefit of U.S. Provisional PatentApplication No. 60/760,157, filed Jan. 20, 2006, the disclosures ofwhich are incorporated herein by reference.

FIELD

The present disclosure in general is related to power conversion, andmore specifically, to a system, apparatus, and method for supplyingpower to solid state lighting devices, such as for providing power tolight-emitting diodes (“LEDs”).

BACKGROUND

A wide variety of off-line power supplies for providing power to LEDsare known. Many of these power supplies (i.e., drivers) are effectivelyincompatible with the existing lighting system infrastructure, such asthe lighting systems typically utilized for incandescent or fluorescentlighting, such as infrastructure generally utilizing phase-modulating“dimmer” switches to alter the brightness or intensity of light outputfrom incandescent bulbs. Accordingly, replacement of incandescent lampsby LEDs is facing a challenge: Either do a complete rewiring of thelighting infrastructure, which is expensive and unlikely to occur, ordevelop new LED drivers compatible with commercially available andalready installed dimmer switches. In addition, as many incandescent orother lamps will likely remain in any given lighting environment, itwould be highly desirable to enable LEDs and incandescent lamps to beable to operate in parallel and under common control.

Incandescent lamps and LEDs can be connected to a common lamp power bus,with the light output intensity controlled using a composite waveform,having two power components. This is complicated, requires excessivelymany components to implement, and is not particularly oriented to AC(alternating current) utility lighting.

An off-line LED driver with a power factor correction capability hasbeen described. When coupled with a dimmer, however, its LED regulationis poor and it does not completely support stable operation of thedimmer in the full range of output loads, specifically when bothincandescent and LED lamps are being used in parallel.

FIG. 1 is a circuit diagram of a prior art current regulator 50connected to a dimmer switch 75 which provides phase modulation. FIG. 2is a circuit diagram of such a prior art (forward) dimmer switch 75. Thetime constant of resistor 76 (RI) and capacitor 77 (C1) control thefiring angle “α” (illustrated in FIG. 3) of the triac 80. The diac 85 isused to maximize symmetry between the firing angle for the positive andnegative half cycles of the input AC line voltage (35). Capacitor 45(C2) and inductor 40 (L1) form a low pass filter to help reduce noisegenerated by the dimmer switch 75. A triac 80 is a switching deviceeffectively equivalent to reverse parallel Silicon Controlled Rectifiers(SCRs) sharing a common gate. The single SCR is a gate-controlledsemiconductor that behaves like a diode when turned on. A signal at thegate (70) is used to turn the triac 80 on, and the load current is usedto hold or keep the triac 80 on. Thus, the gate signal cannot turn anSCR off and it will remain on until the load current goes to zero. Atriac 80 behaves like an SCR but conducts in both directions. Triacshave different turn-on thresholds for positive and negative conduction.This difference is usually minimized by using a diac 85 coupled to thegate 70 of the triac 80 to control the turn-on voltage of the triac 80.

Triacs 80 also have minimum latching and holding currents. The latchingcurrent is the minimum current to turn on the triac 80 when given asufficient gate pulse. The holding current is the minimum current tohold the triac 80 in an on-state once conducting. When the current dropsbelow this holding current, the triac 80 will turn off. The latchingcurrent is typically higher than the holding current. For dimmerswitches that use triacs, capable of switching 3 to 8 A for example, theholding and latching currents are on the order of 10 mA to about 70 mA,also for example and without limitation.

The firing angle (α) of the triac 80 controls the delay from the zerocrossing of the AC line, and is theoretically limited between 0° and180°, with 0° equating to full power and 180° to no power delivered tothe load, with a representative phase-modulated output voltageillustrated in FIG. 3 (as a “chopped” sinusoid). A typical dimmerswitch, for example, may have minimum and maximum a values of about 25°and 155°, respectively, allowing about 98% to 2% of power to flow to theload compared to operation directly from the AC mains (AC line voltage(35)). Similarly, a reverse phase-modulated dimmer will provide anoutput voltage across a resistive load as illustrated in FIG. 4, whichprovides energy to the load at the beginning of each cycle, such as from0° to 90°, for example, with no energy delivered in the latter part ofeach cycle (illustrated as interval β).

Referring to FIG. 2, the firing angle α is determined by the RC timeconstant of capacitor 77 (C1), resistor 76 (R1), and the impedance ofthe load, such as an incandescent bulb or an LED driver circuit (ZLOAD81). In typical dimming applications, ZLOAD will be orders of magnitudelower than RI and resistive, thus will not affect the firing angleappreciably. When the load is comparable to RI or is not resistive,however, the firing angle and behavior of the dimmer switch can changedramatically.

Typical prior art, off-line AC/DC converters that drive LEDs using phasemodulation from a dimmer switch have several problems associated withproviding a quality drive to LEDs, such as: (1) phase modulation from adimmer switch can produce a low frequency (about 120 Hz) in the opticaloutput, referred to as “flicker,” which can be detected by a human eyeor otherwise create a reaction in people to the oscillating light; (2)filtering the input voltage may require quite a substantial value of theinput capacitor, compromising both the size of the converter and itsuseful life; (3) when the triac 80 is turned on, a large inrush currentmay be created, due to a low impedance of the input filter, which maydamage elements of both the dimmer switch 75 and any LED driver; and (4)power management controllers are typically not designed to operate in anenvironment having phase modulation of input voltage and couldmalfunction.

Accordingly, a need remains for an LED driver circuit which can operateconsistently with a typical or standard, forward or reverse,phase-modulating dimmer switch of the existing lighting infrastructureand avoid the problems discussed above, while providing theenvironmental and energy-saving benefits of LED lighting. Such an LEDdriver circuit should be able to be controlled by standard switches ofthe existing lighting infrastructure to provide the same regulatedbrightness, for example, for productivity, flexibility, aesthetics,ambience, and energy savings. A representative LED driver circuit shouldbe able to operate not only alone, but also in parallel with other typesof lighting, such as incandescent, compact fluorescent or otherlighting, and be controllable by the same switches, for example, dimmerswitches or other adaptive or programmable switches used with suchincandescent or other lighting. A representative LED driver circuitshould also be operable within the existing lighting infrastructure,without the need for re-wiring or other retrofitting.

SUMMARY

The embodiments described herein provide numerous advantages. Theembodiments allow for solid state lighting, such as LEDs, to be utilizedwith the currently existing lighting infrastructure, including Edisonsockets, and to be controlled by any of a variety of switches, such asphase-modulating dimmer switches, which would otherwise causesignificant operation problems for conventional switching power suppliesor current regulators. The embodiments further allow for sophisticatedcontrol of the output brightness or intensity of such solid statelighting, and may be implemented using fewer and comparatively lowercost components. In addition, the embodiments may be utilized forstand-alone solid state lighting systems, or may be utilized in parallelwith other types of existing lighting systems, such as incandescentlamps.

The embodiments described herein not only recognize and accommodatevarious states of switches, such as phase-modulating dimmer switches,but further utilize a novel insight to also concurrently recognize andaccommodate various states of a switching power supply, such that both aphase-modulating dimmer switch and a switching power supply operatetogether, seamlessly and with substantial stability. More particularly,the embodiments recognize and accommodate at least three states of aphase-modulating dimmer switch, namely, a first state in which thedimmer switch is not conducting but during which a triggering capacitor(C1, 77) is charging; a second state in which the dimmer switch hasturned on and requires a latching current; and a third state in whichthe dimmer switch is fully conducting and requires a holding current.Concurrently, in combination with the states of the switch, theembodiments recognize and accommodate at least three states, and invarious embodiments four states, of a switching power supply, namely, afirst, start-up state of the switching power supply, during which itgenerates its power supply (VCC voltage level); a second, gradual(graduated or “soft”) start state of the switching power supply, duringwhich it ramps up its provision of power to a load (such as LEDs) (e.g.,through pulse width modulation (“PWM”) switching) from start-up to afull operational mode; a third state, during which the switching powersupply is in a full operational mode; and an optional fourth state,during which the switching power supply may experience an abnormal oratypical operation and enter a protective operating mode. For eachcombination of states of the switch (e.g., dimmer switch) and switchingpower supply, using corresponding criteria for stable operation, theembodiments provide a substantially matching electrical environment tomeet such criteria for stable operation of both the switch and theswitching power supply, enabling seamless and stable operation of bothcomponents. In various embodiments, the same type of substantiallymatching electrical environment may be utilized for multiplecombinations of states, and in other instances, other types ofsubstantially matching electrical environments will be utilized for aselected combination of states of the switch and switching power supply.

The embodiments described herein provide a method of interfacing aswitching power supply to a first switch coupled to an alternatingcurrent (AC) power source for providing power to solid state lighting.In various embodiments, the first switch is a forward or modulateddimmer switch. A representative method comprises: sensing an inputcurrent level; sensing an input voltage level; using a first adaptiveinterface circuit, providing a resistive impedance to the first switchand conducting current from the first switch in a default mode; andusing a second adaptive interface circuit, when the first switch turnson, creating a resonant process and providing a current path during theresonant process of the switching power supply.

In a representative embodiment, the method may further comprise: usingthe second adaptive interface circuit to modulate a current of the firstswitch during the resonant process of the switching power supply; and/orusing a third adaptive interface circuit to modulate a current of thefirst switch during the resonant process of the switching power supply;and/or using the first adaptive interface circuit to conduct currentduring a start-up state or a gradual start state of the switching powersupply; and/or using the first adaptive interface circuit to conductcurrent during charging of a trigger capacitor of the first switch,during turn on of the first switch, and during conduction of the firstswitch.

In various embodiments, the step of providing a resistive impedance mayfurther comprise: switching the first adaptive interface circuit toprovide a constant resistive impedance to the first switch; and/ormodulating the first adaptive interface circuit to provide a variableresistive impedance to the first switch; and/or building an operationalvoltage, and when the operational voltage has reached a predeterminedlevel, modulating the first adaptive interface circuit and transitioningto a gradual start of the switching power supply asynchronously to thestate of the first switch.

In various embodiments, the step of providing a current path during theresonant process may further comprise: determining a peak input currentlevel; and switching a resistive impedance to create the current path.In other various embodiments, the step of providing a current pathduring the resonant process may further comprise: determining a peakinput current level; and modulating a switched, resistive impedance tocreate the current path.

In a representative embodiment, the method may further comprise: duringa full power mode of the switching power supply and during charging of atrigger capacitor of the first switch, operating the switching powersupply at a one-hundred percent duty cycle or in a DC mode. In anotherrepresentative embodiment, the method may further comprise: during afull power mode of the switching power supply and during turning on ofthe first switch, operating the switching power supply at asubstantially maximum instantaneous power for a predetermined period oftime.

In various embodiments, the second adaptive interface circuit comprisesan inductor in parallel with a resistor, and the method may furthercomprise: during a full power mode of the switching power supply andduring turning on of the first switch, operating the switching powersupply at a substantially maximum instantaneous power until the inductorhas substantially discharged.

Also in various embodiments, the method may further comprise: using thesecond adaptive interface circuit to conduct current during a fulloperational power state of the switching power supply; and/or adjustinga minimum power from the first switch during a gradual start phase ofthe switching power supply.

In various embodiments, the second adaptive interface circuit furthercomprises a switchable resistive impedance, and the method may furthercomprise: using the second adaptive interface circuit to provide acurrent path during a start-up phase of the switching power supply,during a gradual start up of the switching power supply, or during afull operational mode of the switching power supply.

In a representative embodiment, the method may further comprise: usingan operational voltage bootstrap circuit coupled to the switching powersupply to generate an operational voltage. The first adaptive interfacecircuit may further comprise the operational voltage bootstrap circuit.

In various embodiments, the method may further comprise: determining amaximum duty cycle corresponding to the sensed input voltage level;providing a pulse width modulation operating mode for the switchingpower supply using a switching duty cycle less than the maximum dutycycle; and when the duty cycle is within a predetermined range of themaximum duty cycle, providing a current pulse operating mode for theswitching power supply. In various embodiments, the method may furthercomprise: determining or obtaining from a memory a maximum duty cyclecorresponding to the sensed input voltage level; and/or determining orvarying the duty cycle to provide a predetermined or selected average orpeak output current level; and/or determining a peak output currentlevel up to a maximum volt-seconds parameter.

In a representative embodiment, the method may further comprise:detecting a malfunction of the first switch. For example, the method maydetect the malfunction by determining at least two input voltage peaksor two input voltage zero crossings during a half-cycle of the AC powersource.

Other embodiments provide a system for power conversion, with the systemcouplable to a first switch (such as a phase-modulated dimmer switch)coupled to an alternating current (AC) power source, and with therepresentative system comprising: a switching power supply comprising asecond power switch; solid state lighting coupled to the switching powersupply; a voltage sensor; a current sensor; a memory; a first adaptiveinterface circuit comprising a resistive impedance to conduct currentfrom the first switch in a default mode; a second adaptive interfacecircuit to create a resonant process when the first switch turns on; anda controller coupled to the voltage sensor, to the current sensor, tothe memory, to the second switch, to the first adaptive interfacecircuit and to the second adaptive interface circuit, and when the firstswitch turns on, the controller to modulate the second adaptiveinterface circuit to provide a current path during the resonant processof the switching power supply.

In various embodiments, the controller further is to modulate the secondadaptive interface circuit to modulate a current of the first switchduring the resonant process of the switching power supply. In arepresentative embodiment, the system may further comprise: a thirdadaptive interface circuit to modulate a current of the first switchduring the resonant process of the switching power supply.

In various embodiments, the controller further is to use the firstadaptive interface circuit to conduct current during a start-up state ora gradual start state of the switching power supply; and/or use thefirst adaptive interface circuit to conduct current during charging of atrigger capacitor of the first switch, during turn on of the firstswitch, and during conduction of the first switch; and/or switch thefirst adaptive interface circuit to provide a constant resistiveimpedance to the first switch; and/or modulate the first adaptiveinterface circuit to provide a variable resistive impedance to the firstswitch.

In a representative embodiment, when an operational voltage has reacheda predetermined level, the controller further may modulate the firstadaptive interface circuit and transition to a gradual start of theswitching power supply asynchronously to the state of the first switch.In various embodiments, the second adaptive interface circuit comprisesa resistive impedance, wherein the controller further may determine apeak input current level, and when the peak input current level has beenreached, the controller further is to switch the resistive impedance tocreate the current path. In other various embodiments, the secondadaptive interface circuit comprises a switched resistive impedance,wherein the controller further may determine a peak input current level,and when the peak input current level has been reached, the controllerfurther is to modulate the switched, resistive impedance to create thecurrent path.

In a representative embodiment, during a full power mode of theswitching power supply and during charging of a trigger capacitor of thefirst switch, the controller further is to operate the switching powersupply at a one-hundred percent duty cycle or in a DC mode; and/orduring a full power mode of the switching power supply and duringturning on of the first switch, the controller further is to operate theswitching power supply at a substantially maximum instantaneous powerfor a predetermined period of time. In another representativeembodiment, the second adaptive interface circuit comprises an inductorin parallel with a resistor, and wherein during a full power mode of theswitching power supply and during turning on of the first switch, thecontroller further is to operate the switching power supply at asubstantially maximum instantaneous power until the inductor hassubstantially discharged.

In various embodiments, the controller further may use the secondadaptive interface circuit to conduct current during a full operationalpower state of the switching power supply. In another embodiment, thecontroller further may adjust a minimum power from the first switchduring a gradual start phase of the switching power supply. In variousembodiments, wherein the second adaptive interface circuit furthercomprises a switchable resistive impedance, and wherein the controllerfurther may use the second adaptive interface circuit to provide acurrent path during a start-up phase of the switching power supply,during a gradual start up of the switching power supply, or during afull operational mode of the switching power supply.

In another embodiment, the system further comprises: an operationalvoltage bootstrap circuit coupled to the switching power supply togenerate an operational voltage. In a representative embodiment, thefirst adaptive interface circuit further comprises the operationalvoltage bootstrap circuit.

In various embodiments, the controller further may determine a maximumduty cycle corresponding to the sensed input voltage level; provide apulse width modulation operating mode for the switching power supplyusing a switching duty cycle less than the maximum duty cycle; and whenthe duty cycle is within a predetermined range of the maximum dutycycle, provide a current pulse operating mode for the switching powersupply. In various embodiments, the controller further may determine orobtain from a memory a maximum duty cycle corresponding to the sensedinput voltage level; and/or may determine or vary the duty cycle toprovide a predetermined or selected average or peak output currentlevel. In a representative embodiment, the controller further maydetermine a peak output current level up to a maximum volt-secondsparameter.

In various embodiments, the controller further may detect a malfunctionof the first switch, for example, by determining at least two inputvoltage peaks or two input voltage zero crossings during a half-cycle ofthe AC power source.

In a representative embodiment, the first adaptive interface circuit maycomprise: a first resistor; a transistor coupled in series to the firstresistor, the transistor having a base or having a gate coupled to thecontroller; and a second resistor coupled to the base or to the gate ofthe transistor.

In another representative embodiment, the first adaptive interfacecircuit may comprise: a first resistor; a transistor coupled in seriesto the first resistor, the transistor having a base or having a gatecoupled to the controller; a second resistor coupled to a source or anemitter of the transistor; and a zener diode coupled to the base or gateof the transistor and coupled to the second resistor.

In a representative embodiment, the second adaptive interface circuitmay comprise: an inductor; and a resistor coupled in parallel to theinductor. In another representative embodiment, the second adaptiveinterface circuit may comprise: an inductor; a first resistor coupled tothe inductor; a transistor having a base or a gate coupled to the firstresistor. In another representative embodiment, the second adaptiveinterface circuit may further comprise: a second resistor coupled to theinductor and coupled to a collector or drain of the transistor; a firstzener diode coupled to an emitter or source of the transistor; and asecond diode coupled to the inductor and to the first zener diode. Inanother representative embodiment, the second adaptive interface circuitmay comprise: an inductor; a first resistor; a differentiator; a oneshot circuit coupled to an output of the differentiator; and atransistor coupled in series to the first resistor and further having agate or base coupled to an output of the one shot circuit.

In various embodiments, the solid state lighting is one or morelight-emitting diodes. The switching power supply may have anyconfiguration, such as having a non-isolated or an isolated flybackconfiguration. The system may have a form factor compatible with an A19standard, such as to fit within an Edison socket. The system may becouplable through a rectifier to the first switch. The system may becouplable through a rectifier and an inductor to the first switch.

In another embodiment, an apparatus is provided for power conversion,the apparatus couplable to a first, phase-modulated dimmer switchcoupled to an alternating current (AC) power source, the apparatuscouplable to a solid state lighting, and with the representativeapparatus comprising: a switching power supply comprising a second powerswitch; a voltage sensor; a current sensor; a memory; a first adaptiveinterface circuit comprising a resistive impedance to conduct currentfrom the first switch in a default mode; a second adaptive interfacecircuit to create a resonant process when the first switch turns on; anda controller coupled to the voltage sensor, to the current sensor, tothe memory, to the second switch, to the first adaptive interfacecircuit and to the second adaptive interface circuit, and when the firstswitch turns on, the controller to modulate the second adaptiveinterface circuit to provide a current path and to modulate a current ofthe first switch during the resonant process of the switching powersupply.

In another embodiment, a system is provided for power conversion, thesystem having a form factor compatible with an A19 standard, the systemcouplable to a phase-modulating dimmer switch coupled to an alternatingcurrent (AC) power source, and with the representative systemcomprising: a switching power supply comprising a power switch; at leastone light-emitting diode coupled to the switching power supply; avoltage sensor to sense an input voltage level; a first adaptiveinterface circuit to conduct current from the dimmer switch in a defaultmode, the first adaptive interface circuit further providing asubstantially matching impedance to the dimmer switch; a second adaptiveinterface circuit to create a resonant process of the switching powersupply and to provide a current path during the resonant process of theswitching power supply; a memory; and a controller coupled to the firstvoltage sensor, to the memory and to the power switch, the controller toprovide a pulse width modulation operating mode using a duty cycle lessthan a maximum duty cycle, and when the duty cycle is within apredetermined range of the maximum duty cycle, to provide a currentpulse operating mode.

Numerous other advantages and features will become readily apparent fromthe following detailed description, from the claims, and from theaccompanying drawings.

DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated as the same become betterunderstood by reference to the following detailed description, whentaken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a circuit diagram illustrating a prior art current regulator;

FIG. 2 is a circuit diagram illustrating a representative prior artdimmer switch;

FIG. 3 is a graphical diagram illustrating the phase-modulated outputvoltage from a standard phase-modulated dimmer switch;

FIG. 4 is a graphical diagram illustrating the phase-modulated outputvoltage from a reverse phase-modulated dimmer switch;

FIG. 5 is a high-level block and circuit diagram illustrating ageneralized prior art current regulator (or converter);

FIG. 6 is a graphical diagram illustrating a triac voltage having asubharmonic startup frequency in a prior art current regulator coupledto a dimmer switch which causes perceptible LED flicker;

FIG. 7 is a graphical diagram illustrating a triac voltage with a 20KOhm load and illustrating premature startup in a prior art currentregulator coupled to a dimmer switch which causes perceptible LEDflicker;

FIG. 8 is a block diagram illustrating a first representative apparatusembodiment and a first representative system embodiment in accordancewith the teachings of the present disclosure;

FIG. 9 is a block diagram illustrating a second representative apparatusembodiment, a second representative system embodiment, and a secondrepresentative adaptive interface embodiment in accordance with theteachings of the present disclosure;

FIG. 10 is a flow diagram illustrating a first representative methodembodiment in accordance with the teachings of the present disclosure;

FIG. 11 is a block and circuit diagram illustrating a thirdrepresentative apparatus embodiment, a third representative systemembodiment, and a third representative adaptive interface embodiment inaccordance with the teachings of the present disclosure;

FIG. 12 is a block and circuit diagram illustrating a fourthrepresentative apparatus embodiment, a fourth representative systemembodiment, and a fourth representative adaptive interface embodiment inaccordance with the teachings of the present disclosure;

FIG. 13 is a graphical timing diagram for switching of a dimmer switch,a representative adaptive interface embodiment, power provided to arepresentative switching power supply, and representative adaptiveinterface power, in accordance with the teachings of the presentdisclosure;

FIG. 14 is a block and circuit diagram illustrating a fifthrepresentative apparatus embodiment, a fifth representative systemembodiment, and a fifth representative adaptive interface embodiment inaccordance with the teachings of the present disclosure;

FIG. 15 is a block and circuit diagram illustrating a sixthrepresentative apparatus embodiment, a sixth representative systemembodiment, and a sixth representative adaptive interface embodiment inaccordance with the teachings of the present disclosure;

FIG. 16 is a block and circuit diagram illustrating a seventhrepresentative apparatus embodiment, a seventh representative systemembodiment, and a seventh representative adaptive interface embodimentin accordance with the teachings of the present disclosure;

FIG. 17 is a block and circuit diagram illustrating an eighthrepresentative apparatus embodiment and an eighth representative systemembodiment in accordance with the teachings of the present disclosure;

FIG. 18 is a flow diagram illustrating a second representative methodembodiment in accordance with the teachings of the present disclosure;

FIG. 19 is a flow diagram illustrating a third representative methodembodiment in accordance with the teachings of the present disclosure;

FIG. 20 is a graphical diagram illustrating representative transientvoltage and current waveforms for a switch turn on in a resonant mode;

FIG. 21 is a graphical diagram illustrating representative, modeledtransient voltage and current waveforms for a fifth representativeapparatus embodiment, a fifth representative system embodiment, and afifth representative adaptive interface embodiment in accordance withthe teachings of the present disclosure;

FIG. 22 is a graphical diagram illustrating representative, modeledtransient voltage and current waveforms for a sixth representativeapparatus embodiment, a sixth representative system embodiment, and asixth representative adaptive interface embodiment in accordance withthe teachings of the present disclosure; and

FIG. 23 is a graphical diagram illustrating representative, modeledtransient voltage and current waveforms for a seventh representativeapparatus embodiment, a seventh representative system embodiment, and aseventh representative adaptive interface embodiment in accordance withthe teachings of the present disclosure.

DETAILED DESCRIPTION

The present disclosure is not intended to limit the invention to thespecific embodiments illustrated. In this respect, it is to beunderstood that the invention is not limited in its application to thedetails of construction and to the arrangements of components set forthabove and below, illustrated in the drawings, or as described in theexamples. Methods and apparatuses consistent with the present inventionare capable of other embodiments and of being practiced and carried outin various ways. Also, it is to be understood that the phraseology andterminology employed herein, as well as the abstract included below, arefor the purposes of description and should not be regarded as limiting.

As mentioned above, prior art LED driver circuits are often problematicwhen utilized with conventional dimmer switches 75, causing problemssuch as perceptible flicker and large inrush currents. For example, asillustrated in FIG. 5, a switching off-line LED driver 90 typicallyincludes a full wave rectifier 20 with a capacitive filter 15, whichallows current to flow to the filter capacitor (C_(FILT)) 15, when theinput voltage is greater than the voltage across the capacitor. Theinrush current to the capacitor is limited by the resistance in serieswith the capacitor. Under normal operating conditions, there may be aNegative Temperature Coefficient resistor (NTC) or thermistor in serieswith the capacitor to minimize inrush current during initial charging.This resistance will be significantly reduced during operation, allowingfor fast capacitor charging. This circuit will continuously peak chargethe capacitor to the peak voltage of the input waveform, 169 V DC forstandard 120 V AC line voltage.

When used with a dimmer switch 75, however, the charging current of thefilter capacitor is limited by the dimming resistance R1 (of resistor76) and is I_(CHARGE)=(V_(IN)−V_(LOAD)−V_(C1))/R1 (FIGS. 2 and 5). Thevoltage across the filter capacitor can be approximated to a DC voltagesource due to the large difference between C1 (77) and C_(FILT) (15).The charging current of the filter capacitor is also the chargingcurrent for C1, which controls the firing angle of the dimmer. Thecharging current for C1 will be decreased from normal dimmer operationdue to the large voltage drop (V_(C1)) across the filter capacitor 15.For large values of V_(C1), the current into C1 will be small and thusslowly charge. As a consequence, and as illustrated in FIG. 6, the smallcharging current may not be enough to charge C1 to the diac 85 breakovervoltage during one half cycle. If the breakover voltage is not reached(93), the triac 80 will not turn on. This will continue through manycycles until the voltage on the filter capacitor is small enough toallow C1 to charge to the breakover voltage. Once the breakover voltagehas been reached (94), the triac 80 will turn on and the capacitor willcharge to the peak value of the remaining half cycle input voltage. Thisphenomenon is illustrated in FIG. 6, requiring four cycles at 60 Hz (92)for this breakover voltage to be reached, such that the triac 80 onlyturns on at a subharmonic frequency, e.g., every 15 Hz as illustrated.

When a dimmer switch is used with a load drawing or sinking a smallamount of current, such that I_(LOAD) is less than the holding currentfor all values of the AC input, the triac 80 will provide inconsistentbehavior unsuitable for applications with LED drivers. The nominalfiring angle will increase due to the increased resistance of Z_(LOAD)81. When the capacitor (C1) voltage exceeds the diac breakover voltage,the diac 85 will discharge the capacitor into the gate of the triac 80,momentarily turning the triac on. Because the load resistance is toohigh to allow the necessary holding current, however, the triac 80 willthen turn off. When the triac turns off, the capacitor C1 beginscharging again through R1 and Z_(LOAD) (81). If there is enough timeremaining in the half cycle, the triac will fire again, and this processrepeats itself through each half cycle. Such premature and unsustainableon-states of a triac 80 are illustrated in FIG. 7, showing the multiplefirings (premature startup attempts) 91 of the triac 80 which can causeperceptible LED flicker.

For a prior art power supply in the normal status of operation, onecomparatively inefficient, prior art method to provide for sufficientcurrent through the dimmer switch 75 is to simply use a load resistor,R_(L), in parallel with (across) the dimmer switch 75, thereby providinga load current of at least V_(TRIAC)/R_(L) when the triac 80 is firing.By setting the resistor values small enough, the current can be madesufficiently high to ensure that it is above the threshold current(typically in the vicinity of 50 mA˜100 mA) needed to keep the triac 80in an on-state. The power dissipation across the resistor R_(L) would beextremely high, i.e., 120²/R_(L) when the phase angle (firing angle α)is small, further resulting in creation of significant heat. Such a loadresistance is typically provided by an incandescent lamp, but is notautomatically provided by an electronic or switchable load, such as aswitching LED driver system.

Further, it is not always necessary to add more current to the triac 80when it is turning on, particularly if multiple lamps are being used(incandescent bulbs or LEDs) which are drawing sufficient current. Thus,in accordance with various representative embodiments, instead of a“dummy” resistor R_(L), active circuitry may be used which is capable ofadjusting according to the needs of the dimmer switch 75. Therepresentative embodiments provide current regulation to allow the triac80 to switch on (fire) and to hold it in an on-state as desired. Therepresentative embodiments are also more power efficient, reducing thesupplemented current (and therefore I²R power loss) when there are otherloads providing or sinking currents or when the phase angle α is small.

While solid state lighting (such as LED lighting) has significantenvironmental and energy-saving benefits, their adoption as the lightingtechnology of choice is less likely if they cannot be integrated into orotherwise made compatible for operation with the existing lightinginfrastructure. In accordance with the present disclosure, therefore, anLED driver circuit is provided which is compatible for operation withthe existing lighting infrastructure, such as dimmer switches, and maybe coupled directly to and controlled by such dimmer switches,regardless of whether other loads, such as additional incandescent orfluorescent lighting, are also coupled to and controlled by such dimmeror other switches. While the representative embodiments are illustratedand discussed below with reference to use with dimmer switches (75), itshould be noted that the representative embodiments are suitable for usewith effectively any types of switching devices or other lightinginfrastructure, except potentially those switches or otherinfrastructure specially designed or implemented for other purposes.

As indicated above, representative embodiments described herein not onlyrecognize and accommodate various states of switches, such asphase-modulating dimmer switches, but further utilize a novel insight toalso concurrently recognize and accommodate various states of aswitching power supply, such that both a phase-modulating dimmer switchand a switching power supply operate together, seamlessly and withsubstantial stability. More particularly, the representative embodimentsrecognize and accommodate at least three states of a phase-modulatingdimmer switch, namely, a first state in which the dimmer switch is notconducting but during which a triggering capacitor (C1, 77) is beingcharged; a second state in which the dimmer switch has turned on andrequires a latching current; and a third state in which the dimmerswitch is fully conducting and requires a holding current, such as for atriac 80 or thyristor. Concurrently, in combination with the states ofthe switch, the representative embodiments recognize and accommodate atleast three states, and in various embodiments four states, of aswitching power supply, namely, a first start-up state of the switchingpower supply, during which it generates its power supply (V_(CC) voltagelevel); a second, gradual start state of the switching power supplyduring which it ramps up its provision of power to a load (such as LEDs)(e.g., through pulse width modulation switching) from start up to a fulloperational mode; a third state, during which the switching power supplyis in a full operational mode; and an optional fourth state, duringwhich the switching power supply may experience an abnormal or atypicaloperation and enter a protective operating mode. For each combination ofstates of the switch (e.g., dimmer switch) and switching power supply,using corresponding criteria for stable operation, the representativeembodiments provide a substantially matching electrical environment tomeet such criteria for stable operation of both the switch and theswitching power supply, enabling seamless and stable operation of bothcomponents. In various representative embodiments, the same type ofsubstantially matching electrical environment may be utilized formultiple combinations of states, and in other instances, other types ofsubstantially matching electrical environments will be utilized for aselected combination of states of the switch and switching power supply.

FIG. 8 is a block diagram of a first representative apparatus 100embodiment, and a first representative system 105 embodiment inaccordance with the teachings of the present disclosure. The apparatus100 provides power to one or more LEDs 140, which may be an array ormultiple arrays of LEDs 140, of any type or color, with the apparatus100 and LEDs 140 forming a first system 105. The apparatus 100 iscompatible with existing lighting infrastructure, and may be coupleddirectly to a dimmer switch 75 for receiving an AC voltage (potentiallyphase-modulated or without any modulation) derived from the AC linevoltage (AC mains) (35), and may be constructed to fit within an A19(e.g., Edison) socket, for example and without limitation. In addition,the apparatus 100 may operate in parallel with other or additional loads95, such as an incandescent lamp or other LEDs 140, under the commoncontrol of the dimmer switch 75.

More generally, the apparatus 100 may be utilized with any existinglighting infrastructure. In addition, it may not be known (such as by amanufacturer) in advance how the apparatus 100 and system 105 will bedeployed by the end user, so such compatibility with any existinglighting infrastructure is a true advantage of the representativeembodiments. For example, a manufacturer, distributor, or other providerof an apparatus 100 will typically not know in advance the types ofswitches to which the apparatus 100 and system 105 may be coupled (e.g.,to a dimmer switch 75, or a non-dimming switch), whether other loads 95may be present, and if so, what types of loads (e.g., incandescent, LED,fluorescent, etc.).

As illustrated, the apparatus 100 comprises one or more sensors 125, oneor more adaptive interfaces 115, a controller 120, a switching powersupply (or driver) 130, a memory (e.g., registers, RAM) 160, andtypically may also comprise a rectifier 110, depending on the type ofswitching power supply 130 utilized. Embodiments or otherimplementations for a controller 120 (and any of its variations, such as120A illustrated below) and a memory 160 are described in greater detailbelow. The one or more sensors 125 are utilized to sense or measure aparameter, such as a voltage or current level, with voltage sensors 125Aand current sensors 125B illustrated and discussed below. For purposesof the present disclosure, it may be assumed that a rectifier 110 ispresent, and those having skill in the art will recognize thatinnumerable other variations may be implemented, are equivalent, and arewithin the scope of the present disclosure. The switching power supply130 and/or the controller 120, in representative embodiments, may alsoand typically will receive feedback from the LEDs 140, as illustrated.One or more adaptive interfaces 115 may be different types and may beplaced in a wide variety of locations within the apparatus 100,depending upon the selected embodiment, such as between the rectifier110 and the dimmer switch 75, in addition to between the rectifier 110and the switching power supply 130, or in parallel with the switchingpower supply 130, or within the switching power supply 130 (and moregenerally, an adaptive interface 115 may have any of the illustratedcircuit locations, such as in series or in parallel with the rectifieror switching power supply (or driver) 130, for example and withoutlimitation), as illustrated in FIG. 8. Representative adaptiveinterfaces 115 and/or their components may be implemented generallyusing active or passive components, or both. One or more sensors 125also may be different types and may be placed in a wide variety oflocations within the apparatus 100, depending upon the selectedembodiment, such as voltage sensors 125A for detection of various inputand/or output voltage levels, or current sensors 125B for detection ofinductor current levels (e.g., within switching power supply 130) and/orLED 140 current, such as the various sensors 125 described in greaterdetail below. It should also be noted that the various components, suchas controller 120, may be implemented in analog or digital form, and allsuch variations are considered equivalent and within the scope of thepresent disclosure. The rectifier 110 may be any type of rectifier,including without limitation, a full-wave rectifier, a full-wave bridge,a half-wave rectifier, an electromechanical rectifier, or another typeof rectifier as known or becomes known in the art. The apparatus 100 andsystem 105 also may be implemented in any form, including in formscompatible with A19 (Edison) or T8 sockets, for example.

In accordance with representative embodiments, dynamic control over theone or more adaptive interfaces 115 is implemented, to account for boththe current state (or timing cycle) of the switching power supply 130and the current state (or timing cycle) of the dimmer switch 75, toprovide for substantially stable operation of the apparatus 100 andsystem 105 without incurring the various forms of flicker or othermalfunctions discussed above. Stated another way, a matching electrical(or electronic) environment is provided for each state of the dimmerswitch 75 (non-conducting and charging a triggering capacitor, turningon with a latching current, and on and conducting with a holdingcurrent) in conjunction with each state of the switching power supply130, such as a start-up state, a gradual or soft start power state, afull operational mode power state, and a protective mode state. Forexample, assuming that a dimmer switch 75 is installed and is notaccessible directly to any sensing and functional manipulations, arepresentative method embodiment provides for interfacing of aphase-modulated dimmer switch 75 and a switching power supply 130 bycontrolling the functionality of the switching power supply 130 in anadaptive timely manner while concurrently recognizing the currentprocess in the dimmer switch 75, and providing a substantially matchingelectrical environment for a stable completion of this dimmer 75 processand transition to another dimmer switch 75 process, such astransitioning from a charging process to a turning on process to aconducting process. Also for example and without limitation, asubstantially matching electrical environment may be provided bycontrolling the switching power supply 130 (e.g., controlling a resonantprocess and current shaping), or by controlling an input impedance ofthe switching power supply 130, or controlling an input current to theapparatus 100, or by controlling an input power of the switching powersupply 130, including control by shutting down the switching powersupply 130.

FIG. 9 is a block diagram of a second representative apparatusembodiment 100A, a second representative system embodiment 105A, and asecond representative adaptive interface embodiment 115A in accordancewith the teachings of the present disclosure. In addition to thecomponents previously discussed with reference to the firstrepresentative apparatus embodiment 100, the second representativeapparatus embodiment is also illustrated as optionally comprising filtercapacitor 235, discussed in greater detail below. As illustrated in FIG.9, a representative adaptive interface 115A comprises one or more offive interface circuits, namely, a start-up interface circuit 200, agradual or soft start power interface circuit 210, a full operationinterface circuit 220, a resonant process interface circuit 195, and aprotective mode interface circuit 230. In any selected embodiment, itshould be noted that the five interface circuits 195, 200, 210, 220,and/or 230 may share common circuitry or be implemented using the samecircuitry, in addition to potentially comprising separate circuits, andmay share common control parameters in some instances as well. Whileillustrated as located between a rectifier 110 and the switching powersupply 130, as discussed above, the representative adaptive interface115A and/or its component interfaces 195, 200, 210, 220, and/or 230 mayhave any of various circuit locations within an apparatus 100A, inaddition to or in lieu of those illustrated.

As mentioned above, concerning the representative adaptive interface115A, we can distinguish at least four independent functional phases orstates of the switching power supply 130, in conjunction with at leastthree operational states of a dimmer switch 75. The representativeadaptive interface 115A recognizes and accommodates the variouscombinations of states of the dimmer switch 75 and the switching powersupply 130 using one or more of the component interfaces 195, 200, 210,220, and/or 230. During switching power supply 130 start up,representative start-up interface circuit 200 is utilized for creatingan operational voltage (V_(CC)) for a power supply controller 120,during which all other switching power supply 130 circuits are disabledand energy consumption is comparatively small, and for providing orallowing sufficient current to the dimmer switch 75 for any of its threestates. During a gradual or soft start for supplying power by theswitching power supply 130, as an electrical process of supplyingincreasing levels of energy to the output load (LEDs 140), and energyconsumption is comparatively small energy, gradual or soft start powerinterface circuit 210 is utilized to allow both ramping up of outputenergy and sufficient current to the dimmer switch 75 for any of itsthree states. During full operation of the switching power supply 130,having nominal energy consumption, resonant process interface circuit195 and full operation interface circuit 220 are utilized to providecurrent shaping (generally controlling input current levels) and alsoallow sufficient current to the dimmer switch 75 for any of its threestates. A protective mode of operation, in which the switching powersupply 130 or its various components are shut down and energyconsumption is comparatively small, is also implemented using protectivemode interface circuit 230, which, depending upon the selectedembodiment, may also effectively shut down the dimmer switch 75 or mayallow sufficient current to the dimmer switch 75 for any of its threestates.

By controlling the adaptive interface 115 and/or its componentinterfaces 195, 200, 210, 220 and/or 230, the various processes (orstates) of the dimmer switch 75 are also controlled, including withoutlimitation: (a) the charging of the triggering capacitor (C1) 77 andfiring of the diac (D1) 85 (and, in order to preserve the dimmer switch75 mechanical position (value of R1) related to the desired dimminglevel provided by the user, the external impedance of charging circuit(input impedance of the apparatus) is substantially close to oneprovided by an incandescent bulb (e.g., Z_(LOAD) 81), and no energy issupplied to the power supply); (b) the turning on of the dimmer switch75 (e.g., triac 80) with a substantially minimum current nonethelesssufficient to exceed the triac 80 latching current, which involves atransient input to the apparatus 100 from zero power to any powersourced by AC line 35; and (c) the conducting of the current through thedimmer switch 75 (triac 80) through the end of the current AC cycle(e.g., until zero voltage during the phase cc, which may be referred toequivalently (although inexactly) as a zero crossing) with a current asmay be needed and nonetheless sufficient to exceed the triac 80 holdingcurrent with any power sourced by the AC line to the switching powersupply 130. For a reverse dimmer, the charging process ((a) above)generally follows the conducting process ((c) above), and those havingskill in the art will recognize the application of the representativeembodiments and principles taught herein to such situations.

FIG. 10 is a flow diagram of a first representative method embodiment inaccordance with the teachings of the present disclosure. The variousstates of the switching power supply 130 and the dimmer switch 75 may beviewed as forming a matrix, such that the functionality of the switchingpower supply 130 is controlled in a timely and adaptive manner,recognizing the current process of the dimmer switch 75, the currentstate of the switching power supply 130, and providing a correspondingsubstantially matching electrical environment for substantially stableoperation of the dimmer switch 75, the provision of appropriate power tothe LEDs 140, and the corresponding substantially stable transition fromstate to state. Referring to FIG. 10, the method begins with the turningon of the AC line, such as by a user mechanically turning on a dimmerswitch 75, start step 300. The apparatus 100, 100A (or the otherapparatus embodiments discussed below) (and/or the controller 120, 120A)then determines the functional status of the switching power supply 130,whether it is in any of the four states mentioned above, a protectivemode, full operational mode, gradual or soft start mode, or by defaultin a start-up mode (steps 302, 304, 306, and 308). For each of thesepossible states of the switching power supply 130, a state of the dimmerswitch 75 is determined (e.g., through one or more sensors 125), and acorresponding substantially matching electrical environment is providedfor the combination of states of both the switching power supply 130 andthe dimmer switch 75. Stated another way, for each of four states of theswitching power supply 130, one or more substantially matchingelectrical environments is provided when the triggering capacitor 77(C1) is being charged (steps 310, 316, 322, and/or 328), or when thedimmer switch 75 (triac 80) is turning on (steps 312, 318, 324, and/or330), or when current is being conducted through the dimmer switch 75(steps 314, 320, 326, and/or 332). Following steps 314, 320, 326, and/or332, the method determines whether the AC line (dimmer switch 75) hasbeen turned off, step 334, and if not, the method returns to step 302and iterates, and if so, the method may end, return step 336. As aconsequence, the apparatus 100, 100A (or the other apparatus embodimentsdiscussed below) provides a substantially matching electricalenvironment corresponding to both the state of the dimmer switch 75 andthe switching power supply 130. The various combinations of states,monitoring of states, and provision of substantially matching electricalenvironments is discussed in greater detail below.

For each of these 12 combinations of states or processes, and dependingon the intended deployment (e.g., 110 V, 220 V), correspondingparameters are predetermined and stored in memory 160, and then insubsequent operation, are retrieved from the memory 160 and utilized bythe controller 120 to provide the corresponding substantially matchingelectrical environment. As mentioned above, a substantially matchingelectrical environment may be provided by the controller 120 bycontrolling the switching power supply 130 (e.g., controlling a resonantprocess, current shaping, and other methods discussed below), or bycontrolling an input impedance of the switching power supply 130, orcontrolling an input current to the apparatus 100, or by controlling aninput power of the switching power supply 130, including control byshutting down the switching power supply 130, for example and withoutlimitation. It should be noted, however, that for various combinationsof states, the corresponding parameters and/or types of control may besubstantially similar of the same, depending on the selected embodiment.The corresponding parameters and/or types of control may be determinedin a wide variety of ways, such as based upon minimum voltage levels forany and/or all countries, component values, maximum voltage levels to betolerated by a switching power supply 130 and/or LEDs 140,characteristics of dimmer switches 75 (such as minimum holding andlatching currents), etc., with representative methods of predeterminingcorresponding parameters discussed in greater detail below. For exampleand without limitation, a minimum current parameter (e.g., 50 mA) may beutilized and sensed via a current sensor 125B, with a controller 120,120A then providing corresponding gating or modulation of the variousswitches and other circuits comprising an adaptive interface 115 toensure such minimum current flow. Accordingly, as the dimmer switch 75and switching power supply 130 change their respective functionalstatuses, the inventive method implemented by an apparatus 100, 100A-G(or the other apparatus embodiments discussed below) automaticallyadapts and adjusts using a new set of corresponding parameters for thecorresponding combination of states of the dimmer switch 75 andswitching power supply 130.

For example, a method of interfacing a power supply 130 powered througha dimmer switch 75 during the start-up state of an apparatus 100, 100A-G(switching power supply 130), by providing a substantially matchingelectrical environment, may comprise the following sequence (FIG. 10,steps 310-314):

-   -   1. Monitoring the status of the dimmer switch 75 (steps        310-314).    -   2. Recognizing that the dimmer switch 75 status is that of        charging its triggering capacitor 77 (step 310).    -   3. Providing a comparatively low impedance to the dimmer switch        75 (steps 310-314), thereby allowing sufficient current to flow        to charge the triggering circuitry, and further effectively        emulating an incandescent lamp. For example, the provided        impedance can be constant with a maximum value to create current        at dimmer switch 75 turn on slightly exceeding the latching and        holding current thresholds (steps 312-314). The matching        impedance, in the case of an available independent control        voltage, can be adaptive, changing its value based on triggering        circuit charge time to sink the current slightly over latching        and holding current thresholds, which may be correspondingly        defined at the values of instantaneous AC voltage at dimmer turn        on.    -   4. Sensing when the dimmer switch 75 is turned on and        conducting, and continuing to provide the matching impedance to        the dimmer switch 75 to sink current slightly over holding        current threshold (step 312).    -   5. Starting a process of building an operational voltage for the        apparatus 100, 100A-G (by active or passive circuits), such as        to provide an operating voltage (VCC) to the controller 120. The        provided matching interface impedance(s) will remain activated        through this process which may take a few complete sequential        cycles of the dimmer switch 75, namely, charging the triggering        capacitor 77, turning the dimmer switch 75 (triac 80) on and        conducting current through the dimmer switch 75 (steps 310-314).    -   6. Monitoring the level of the operational voltage of the        apparatus 100, 100A-G.    -   7. At a power-on reset threshold voltage level, enabling the        controller 120 and transitioning to the gradual or soft start of        the switching power supply 130.    -   8. Continuing providing a matching impedance(s) to the dimmer        switch 75 to charge triggering capacitor, turn on the dimmer        switch 75 and adaptively sink sufficient current over the        latching and then holding current thresholds during the        transition to gradual or soft start (steps 310-314).

Accordingly, during start up of the apparatus 100, 100A-G and itsincorporated switching power supply 130, for any state of the dimmerswitch 75, an interface circuit (e.g., 115, 200, 210, and/or the othersdiscussed below) is utilized for providing an appropriate impedance toallow sufficient current for the corresponding state of the dimmerswitch 75, thereby generating a corresponding, substantially matchingelectrical environment for each combination of states.

FIG. 11 is a block and circuit diagram of a third representativeapparatus embodiment 100B, a third representative system embodiment105B, and a third representative adaptive interface embodiment 115B inaccordance with the teachings of the present disclosure. Not separatelyillustrated, the apparatus 100B may be coupled to a dimmer switch 75 andan AC line 35 as previously illustrated in FIGS. 8 and 9. For exampleand without limitation, the third representative adaptive interfaceembodiment 115B may be utilized during start up, gradual or soft startand other processes (and states of the switching power supply 130), andmay be utilized to implement either or both a start-up interface circuit200, a gradual or soft start power interface circuit 210, and/or a fulloperation interface circuit 220, for example and without limitation.Referring to FIG. 11, third representative adaptive interface embodiment115B comprises a resistive impedance (resistor 202), switch 205 andoptional resistor 203, with the resistor 202 connected to the dimmerswitch 75 (and in parallel with the switching power supply 130) by theswitching of a switch (depletion mode MOSFET) 205, which is on andconducting without the provision of any control signal from thecontroller 120, providing a comparatively low impedance as asubstantially matching electrical environment and further providing thecomparatively low impedance as a default mode, such as during V_(CC)generation (steps 310-314) or during gradual or soft start (steps316-320). Providing such a comparatively low impedance as a default modeserves to ensure that the dimmer switch 75 functions properly and hassufficient trigger capacitor charging, latching, and holding currents,provided through the resistive impedance (resistor 202) and switch 205,such as when the controller 120 and switching power supply 130 aregenerating their respective operational voltages and may not yet befully functional, e.g., when the dimmer switch 75 is initially turned onby a user. If during this initial start-up time interval the controller120 has an independent voltage source (such as a battery) or it developsan operational voltage, the controller 120 may change (adapt) thisimpedance to the optimal conditions for dimmer performance, as may besensed by a voltage and/or current sensor 125A, 125B. Following suchstart up, the controller 120 may provide a control signal to the gate ofthe switch (MOSFET) 205, such as to modulate the current flow throughresistor 202 and switch 205, such as for gradual or soft start powermode of the switching power supply 130, or to decrease or terminate theadditional current flow through adaptive interface embodiment 115B, suchas during full operational mode of the switching power supply 130 whensufficient current may be drawn by the switching power supply 130. Thoseskilled in the art, using principles of this disclosure, may suggest avariety of other circuits to provide a comparatively low resistiveimpedance to the dimmer without any control signal for such a start-upprocess and a default mode.

During gradual or soft start of the system 105B (FIG. 11), thecontroller 120 ramps up power to the load (LEDs) 140 compatible with thestable operation of the apparatus 100B (and other apparatuses 100, 100A,100C-G). Typically at or during gradual or soft start, the operatingswitching frequency, output voltage and output current are increasing. Asignificant parameter for the adaptive interface 115B is increasinginput power to the switching power supply 130 from levels below thematching of the minimum needs of the dimmer switch 75 to the levels farexceeding that minimum level to provide power to the LEDs 140. Arepresentative method of a gradual or soft start up of a switching powersupply 130 powered by a dimmer switch 75, by providing a substantiallymatching electrical environment to the dimmer switch 75, such as usinginterface 115B providing a resistive impedance, may comprise thefollowing sequence (FIG. 10, steps 316-320):

-   -   1. Transitioning from a start-up stage to a gradual or soft        start stage asynchronously to the state of the dimmer switch 75,        i.e., gradual or soft start may commence regardless of the state        of the dimmer switch 75, such as when the dimmer switch 75 is in        any one of its three cyclical states of charging its triggering        capacitor, turning on the dimmer switch 75, or conducting        current through the dimmer switch 75.    -   2. Continuing providing (via an adaptive interface 115) a        substantially matching electrical environment (as with the case        for the power supply 130 start up), such as using interface        115B, to keep the dimmer switch 75 operation stable in each of        its possible three states until the input voltage is        substantially zero (e.g., a zero crossing).    -   3. Monitoring the status of the dimmer switch 75 after a zero        crossing, such that if the dimmer switch 75 is off (a forward        dimmer), providing a matching resistive impedance to the        triggering circuit of the dimmer 75 via an adaptive interface        115, and if the dimmer switch 75 is on (a reverse dimmer),        providing a matching adaptive power sink to the dimmer via an        adaptive interface 115. The total matching power sink to the        dimmer switch 75 is equal to the sum of input power of the        switching power supply 130 and additional power consumed by an        adaptive interface 115. Representative matching adaptive power        sinks are discussed in greater detail below with reference to        FIGS. 14-16.    -   4. Monitoring a change of the dimmer switch 75 status from        charging to turning on and conducting current for a forward        dimmer and providing a matching adaptive power sink to the        dimmer switch 75 via an adaptive interface 115 and providing a        matching resistive impedance to a triggering circuit of a        reverse dimmer.    -   5. Cyclically changing the dimmer matching electrical        environment compatible with and corresponding to the dimmer        switch 75 cyclical status.    -   6. Phasing the additional current drawn by an adaptive interface        115 to zero as input power of the switching power supply 130        increases and goes over a minimum level for ongoing stable        operation of the dimmer switch 75.    -   7. Transitioning to a full operation power mode and        discontinuing operations of applicable adaptive interfaces 115        as necessary or desirable.

Accordingly, during gradual or soft start of the apparatus 100, 100A-G,and its incorporated switching power supply 130, for any state of thedimmer switch 75, an interface circuit (e.g., 200, 210 and/or the othersdiscussed below) is utilized for providing an appropriate impedance toallow sufficient current for the corresponding state of the dimmerswitch 75 and to provide current shaping/control during dimmer turn on(as discussed in greater detail below), thereby generating acorresponding, substantially matching electrical environment for eachcombination of states. As the switching power supply 130 ramps up to afull operational mode, the additional current sinking provided by theadaptive interface 115 is decreased, while concurrently maintainingsufficient current through the dimmer switch for any of its charging,turning on, and conducting states.

FIG. 12 is a block and circuit diagram of a fourth representativeapparatus embodiment 100C, a fourth representative system embodiment105C, and a fourth representative adaptive interface embodiment 115C inaccordance with the teachings of the present disclosure. Not separatelyillustrated, the apparatus 100C may be coupled to a dimmer switch 75 andan AC line 35 as previously illustrated in FIGS. 8 and 9. FIG. 13 is agraphical timing diagram for representative switching of a dimmerswitch, a representative adaptive interface 115 embodiment, powerprovided to a representative switching power supply 130, andrepresentative adaptive interface power utilization, in accordance withthe teachings of the present disclosure. For example and withoutlimitation, the fourth representative adaptive interface embodiment 115Cmay be utilized during both start up and gradual or soft start processesfor any state of the dimmer switch 75 (steps 310-320), it also may beutilized during full operational mode (step 322), and may be utilized toimplement either or both a start-up interface circuit 200 and/or agradual or soft start power interface circuit 210, for example andwithout limitation. The fourth representative adaptive interfaceembodiment 115C comprises a matching resistive impedance 207 and 208connected to the dimmer switch 75 by a switch (MOSFET) 215, to provide asubstantially matching electrical environment for the dimmer switch 75(for any of its three states) during start up and/or during gradual orsoft start of the switching power supply 130. This matching resistiveimpedance can be either constant by using a gate-to-source voltagedefined by an optional zener diode 211, or variable and driven by acontrol voltage from controller 120. The dimmer switch 75 status issensed by the voltage sensor 125A in this representative embodiment.When the dimmer switch 75 is turning on, the controller 120 regulatesthe current sink circuit formed by resistors 207, 208, 212, 213 andswitch (MOSFET) 215. The adaptive interface 115C is effectivelyregulating the input power to the system 105C such that the minimumcurrent to be put through the dimmer switch 75 for its stable operationis exceeded. As gradual or soft start of the switching power supply 130progresses to its full operational state and when the dimmer switch 75is on and conducting, the additional power consumed by an adaptiveinterface 115C is gradually phased out to zero, as illustrated in FIG.13.

Accordingly, during either start up or gradual or soft start states ofthe switching power supply 130, an adaptive interface 115, such as 115Bor 115C, provides a corresponding and substantially matching electricalenvironment to the dimmer switch 75, such as a constant or variableimpedance allowing sufficient current through the dimmer switch 75 to begreater than or equal to a latching or holding current (when the dimmeris turning on or is in an on-state, steps 312, 314, 318, and/or 320) andto provide a current path for charging the triggering capacitor (whenthe dimmer is in an off or non-conducting state, FIG. 10, steps 310,316). During full operational mode of the switching power supply 130,such a substantially matching electrical environment to the dimmerswitch 75, such as a constant or variable impedance, may also be used toprovide a current path for charging the triggering capacitor (when thedimmer is in an off or non-conducting state, FIG. 10, step 322).

A substantially matching electrical environment is also provided,actively (dynamically) or passively, during the full operational mode ofthe switching power supply 130. In various representative embodiments, aresonant mode is created for controlling an inrush, peak current whenthe dimmer switch 75 turns on, which is further actively modulated toavoid excessive current levels while concurrently maintaining minimumlatching and holding currents for the dimmer switch 75, as discussed ingreater detail below. Referring again to FIG. 9, an optional filtercapacitor 235 may be implemented to provide power factor correction, forexample. The filter capacitor 235 may be connected after the rectifier110 as illustrated, or between the rectifier 110 and the dimmer switch75. Inclusion of such a filter capacitor 235, however, can serve toextend and delay the charging time for the triggering capacitor 77.Various modeling has shown, for example, that a 3.4 ms delay forcharging the triggering capacitor 77 when connected to an incandescentbulb may be extended to 4.2 ms when such a filter capacitor 235 isutilized, potentially leading to non-triggering of the diac 85 due to alow voltage on triggering capacitor 77, even after one-half cycle ofcharging. To avoid undue delay in charging of the triggering capacitor77, in accordance with the representative embodiments, the capacitanceof the filter capacitor 235 should not exceed the capacitance of thetriggering capacitor 77 by more than three orders of magnitude. In arepresentative embodiment, the filter capacitor 235 is comparativelysmall, on the order of about 0.5-2.5 μF, and more particularly on theorder of about or substantially 0.1-0.2 μF in various representativeembodiments, as a larger filter capacitor 235 would interfere withcharging of the triggering capacitor (77).

Use of such a comparatively small filter capacitor 235, however, withoutadditional components provided in the representative novel embodimentsand discussed below, would allow for a substantial and potentiallyexcessive peak current into the switching power supply 130 when thedimmer switch 75 is turned on, which may be harmful to the switchingpower supply 130, among other things. Accordingly, to avoid such a peakinrush current, representative embodiments create and modulate aresonant process during full operational mode of the switching powersupply 130 when the dimmer switch 75 is turning on (FIG. 10, step 324),such as by using an adaptive interface 115D, 115E, and/or 115F, asillustrated and discussed in greater detail below with reference toFIGS. 14-16 and FIGS. 20-23. Such creation and modulation of a resonantprocess may also be utilized during other states of the switching powersupply 130 and dimmer switch 75, such as during gradual or soft startwhen the dimmer switch 75 is turning on (step 318) and otherwise duringthe transition from gradual or soft start to full operational mode.

Representative apparatus 100B and 100C also comprise a voltage sensor125A which may be utilized to sense the status of the dimmer switch 75.Alternatively, other types of sensors 125 may also be utilizedequivalently to determine the status of the dimmer switch 75. When thesensor 125 indicates that the dimmer switch 75 is off due to zerovoltage of a forward dimmer or the dimmer turning off for a reverse typeof dimmer, the voltage across the input filter capacitor 235 drops to avery small value. At about this time, during full operational mode, thecontroller 120 turns on at least one switch of the switching powersupply 130 (e.g., 285 in FIG. 17) which is series connected to the inputvia at least one magnetic winding (and as illustrated by the primarywinding of flyback transformer 280 in FIG. 17 or an inductor such asinductor 236 of FIGS. 14-16). Due to the comparatively small values ofthe capacitance of the filter capacitor 235 and inductance of inductorsin the switching power supplies working in the practical range offrequencies from 50 kHz to 1 MHz, the external impedance to charge thetriggering capacitor 77 is comparatively small and is in the range of anincandescent bulb value, thereby allowing sufficient current to chargethe triggering capacitor 77 (FIG. 10, step 322). Accordingly, duringfull operational mode and the transition to full operational mode fromgradual or soft start, during charging of the triggering capacitor 77,circuits within the switching power supply 130 may be utilized to ensuresufficient charging current (in addition to ensuring sufficient latchingand holding currents), without requiring additional resistive impedancesor current sinks, etc., to draw additional current for this purpose.

A representative first method of operating an apparatus having aswitching power supply 130 and an input filter capacitor 235 (having acomparatively low capacitance, i.e., a small capacitor) during a fulloperation mode and when powered by a dimmer switch 75, by providing asubstantially matching electrical environment to the dimmer switch 75,may comprise the following sequence (FIG. 10, step 322):

-   -   1. Monitoring the status of the dimmer switch 75.    -   2. When the dimmer switch 75 has turned off, turning on the        primary switch of the switching power supply 130 in a first        switching mode with a substantially maximum practical duty cycle        (up to 100%) (FIG. 10, step 322) (and also effectively providing        an additional current path to allow charging of the triggering        capacitor, such as using an adaptive interface 115, as may be        necessary or desirable, for example, based on monitoring of        voltage or current levels (e.g., 115B, 115C)). For such charging        of the triggering capacitor during full operational mode, it        should be noted that components internal to the switching power        supply 130 may be utilized to provide the current path to allow        such charging, rather than other additional components.    -   3. Continuing switching the switching power supply 130 in the        first mode with the substantially maximum duty cycle if it is        less than one-hundred percent (100%), or keeping it in a DC mode        if it is 100%.    -   4. When the dimmer switch 75 turns on, operating the switching        power supply 130 in a second switching mode having the duty        cycle determined by feedback from the switching power supply        130, such as via voltage or current sensors 125A, 125B, or        feedback from another circuit component, such as LED 140        current.

As mentioned above, a magnetic winding of some kind, such as an inductor236 or transformer, will be connected in series to the rectifier 110 atsome point during the switching cycle of the switching power supply 130.Inclusion of such a filter capacitor 235 and magnetic winding (inductor236) may serve to reduce the reliability of the performance of a dimmerswitch 75 without the introduction of a corresponding substantiallymatching electrical environment in accordance with the representativeembodiments, using methods in addition to those discussed for the startup and gradual or soft start functional phases of the switching powersupply 130, to provide for a more optimal performance of the switchingpower supply 130 during full operational mode (following gradual or softstart).

FIG. 20 is a graphical diagram illustrating representative voltage andcurrent waveforms for a switch turn on in a resonant mode if an inductoror other magnetic winding, without additional circuitry, is included,such as for the circuit of FIG. 14 if resistor 237 were not included(contrary to various representative embodiments). While the peak current611 and voltage 612 waveforms are damped oscillations and by includingan inductor 236 are now below excessive current levels, during the timeinterval of t3 to t4, another problem may be created, as the illustratedmodeling indicates that dimmer switch 75 current is substantially zero,potentially resulting in a malfunction of the dimmer switch 75 andcausing perceptible flicker.

Various experimental modeling and theoretical analyses indicate,however, that with typical inductance and capacitance values of a priorart switching power supply, because the filter capacitor 235 is likelydischarged by the time the dimmer switch 75 turns on, the turning on ofthe dimmer switch 75 will produce transient voltage and current levelswhich may create an unstable, oscillatory interface with the dimmerswitch 75. To avoid such an unstable, oscillatory interface with thedimmer switch 75, a substantially matching electrical environment isintroduced in accordance with the representative embodiments, using anadaptive interface 115D which shapes or otherwise alters the currentprovided through the dimmer switch 75. FIG. 14 is a block and circuitdiagram of a fifth representative apparatus embodiment 100D, a fifthrepresentative system embodiment 105D, and a fifth representativeadaptive interface embodiment 115D in accordance with the teachings ofthe present disclosure. FIG. 21 is a graphical diagram illustratingrepresentative, modeled transient voltage 616 and current 615 waveformsfor a fifth representative apparatus embodiment, a fifth representativesystem embodiment, and a fifth representative adaptive interfaceembodiment in accordance with the teachings of the present disclosure.Not separately illustrated, the apparatus 100D may be coupled to adimmer switch 75 and an AC line 35 as previously illustrated in FIGS. 8and 9. The adaptive interface 115D is a representative passiveembodiment of a full operation interface circuit 220, for example andwithout limitation. The adaptive interface 115D comprises a resistor 237connected in parallel with inductor 236, and the inductor 236 andcapacitor 235A form a resonant circuit. When the resonant currentreaches its peak, the voltage across the inductor 236 changes polarityand partially discharges through the resistor 237, thereby diminishingthe inrush current into the switching power supply 130 and preventingcurrent to further charge filter capacitor 235A, while simultaneouslyallowing sufficient latching and holding currents for the dimmer switch75. Adaptive interface 115D provides a passive implementation of themethod of interfacing of the dimmer switch 75 and switching power supply130 by providing a substantially matching electrical environment throughshaping dimmer switch 75 current in the resonant process and provideslatching and holding currents well above any typical minimum value for adimmer switch 75. As illustrated in FIG. 21, experimental modelingindicates significant damping and effective elimination of any unwantedoscillation following switch turn on (waveform 613), and further mayprovide a minimum dimmer switch 75 current of about 96 mA (currentwaveform 615), a value above typical holding current levels (e.g., 50mA), while latching current has been shown to be about 782 mA, also wellabove the typical minimum latching current threshold.

In accordance with representative embodiments, the inductance andcapacitance values of the resonant components outside the dimmer switch75 (or otherwise a characteristic impedance, such as about the 250 Ohmvalue mentioned below) are predetermined or preselected in such way thatthe peak resonant current both exceeds the value of the latching currentof the dimmer switch 75 at any AC value at turn on, and further isreasonably or comparatively low in order to avoid damaging dimmer switch75 and switching power supply 130 components. For a 110 V (220 V)operating environment, one or more inductors having a combinedinductance of about 16-24 mH (40-50 mH), and more particularly 18-22 mH(43-47 mH), are utilized (e.g., three inductors implementing inductor236 at 6.8 mH each (15 mH each)), for the previously stated range ofcapacitance values for the filter capacitor 235, providing an overallcharacteristic impedance between about 200-300 Ohms, and moreparticularly, generally about 250 Ohms.

A representative second method of operating an apparatus 100, 100A-Ghaving a switching power supply 130 and an input filter capacitor 235(having a comparatively low capacitance, i.e., a small capacitor) duringa full operation mode and when powered by a dimmer switch 75, byproviding a substantially matching electrical environment to the dimmerswitch 75 when it has turned on, may comprise the following sequence(FIG. 10, step 326 or both steps 324-326):

-   -   1. Monitoring resonant current after dimmer switch 75 turn on.    -   2. When the resonant current has reached its peak, adaptively        providing a first interface mode using an adaptive interface 115        (e.g., 115E, 115F) as an additional transient path for the        current to divert it from resonant charging of the filter        capacitor 235 while simultaneously maintaining the dimmer switch        75 current above the holding (or latching) current threshold.    -   3. With the adaptive interface 115 (as an additional transient        circuit) activated, driving the switching power supply 130 with        the substantially maximum permissible instantaneous input power        without violation of the subsequent average power consumed by        the switching power supply 130 during the utility cycle as        determined or set by corresponding feedback.    -   4. Discontinuing use of the adaptive interface 115 and        transitioning to a second interface mode of the dimmer switch 75        and the switching power supply 130 at about the time the        resonant inductor has discharged its stored energy or when a        predetermined period of time has elapsed following the resonant        current having substantially reached its peak.

This representative methodology may be implemented, for example, usingthe circuitry illustrated in FIGS. 15-17.

FIG. 15 is a block and circuit diagram of a sixth representativeapparatus embodiment 100E, a sixth representative system embodiment105E, and a sixth representative adaptive interface embodiment 115E inaccordance with the teachings of the present disclosure. FIG. 22 is agraphical diagram illustrating representative, modeled transient voltage621 and current 620, 622 waveforms for a sixth representative apparatusembodiment, a sixth representative system embodiment, and a sixthrepresentative adaptive interface embodiment in accordance with theteachings of the present disclosure. Not separately illustrated, theapparatus 100E may be coupled to a dimmer switch 75 and an AC line 35,as previously illustrated in FIGS. 8 and 9. The adaptive interface 115Eimplements a full operation interface circuit 220, for example andwithout limitation. The adaptive interface 115E comprises inductor 236,resistors 238 and 239, switch (transistor) 240, zener diode 241, andblocking diode 242. The inductor 236 and filter capacitor 235A form aresonant circuit. A transistor 240 is connected in series with theresistor 239 and diodes 241 and 242 across (in parallel with) theinductor 236. The base of transistor 240 is also connected to theinductor 236 via a resistor 238. Blocking diode 242 and zener diode 241prevent a turning on of the transistor 240 during the non-resonant (ornon-transient) switching cycles of the power supply 130. When theresonant current through the dimmer switch 75 reaches its peak, thepolarity of the voltage across inductor 236 changes and transistor 240starts conducting, providing a transient current path through resistor239 and preventing excessive overcharge of the filter capacitor 235A. Asillustrated in FIG. 22, experimental modeling (voltage waveform 621across filter capacitor 235, modeled voltage waveform 623 provided bydimmer switch 75, current 620 through dimmer switch 75, and current 622through transistor 240) indicates significant damping and effectiveelimination of any unwanted oscillation, providing substantially stableoperation of the dimmer switch 75, and further provides both a maximumcurrent of about 1.07 A and a minimum dimmer switch 75 current of about156 mA, a value above typical minimum holding and latching currentthresholds.

FIG. 16 is a block and circuit diagram of a seventh representativeapparatus embodiment 100F, a seventh representative system embodiment105F, and a seventh representative adaptive interface embodiment 115F inaccordance with the teachings of the present disclosure. FIG. 23 is agraphical diagram illustrating representative, modeled transient voltageand current waveforms for a seventh representative apparatus embodiment,a seventh representative system embodiment, and a seventh representativeadaptive interface embodiment in accordance with the teachings of thepresent disclosure. Not separately illustrated, the apparatus 100F maybe coupled to a dimmer switch 75 and an AC line 35 as previouslyillustrated in FIGS. 8 and 9. The adaptive interface 115F implements afull operation interface circuit 220, for example and withoutlimitation. The adaptive interface 115F comprises inductor 236,differentiator 261, one shot circuit 252, switch (MOSFET transistor)250, and resistor 251. A current sensor 125B is illustrated as embodiedby and comprising a current sense resistor 260, which is illustrated asproviding feedback to the differentiator 261 and also optionally to thecontroller 120. In addition to the other control functionality of acontroller 120 as discussed herein, controller 120A may further comprisea differentiator 261. A voltage generated across current sense resistor260 may be utilized as an indicator of, for example, current through thedimmer switch 75 (not separately illustrated). Inductor 236 and inputfilter capacitor 235A also form a resonant circuit as discussed above. Adifferentiator 261 comprising operational amplifier 255, capacitor 256,and resistors 253 and 254, is connected (via capacitor 256 to itsinverting input) to current sense resistor 260. The output of thedifferentiator 261 is coupled to a one shot circuit 252 to drive theswitch (MOSFET) 250 with a resistive load 251. When the resonant currentthrough the dimmer switch 75 reaches its peak, the differentiator 261triggers the one shot circuit 252, which turns on switch (MOSFET) 250for a predetermined or preselected time duration, providing anadditional path for current from inductor 236, to avoid additionalcharging of filter capacitor 235A. The various waveforms illustrated inFIG. 23 include current waveform 630 for the current through the dimmerswitch 75, voltage waveform 631 for the voltage across the filtercapacitor 235A, the input AC voltage waveform 623 (when turned on by thedimmer switch 75), and the current waveform 632 for the current throughthe MOSFET switch 250. Experimental modeling indicates significantdamping and effective elimination of any unwanted oscillation, providingsubstantially stable operation of the dimmer switch 75, and further mayprovide a minimum dimmer switch 75 current of about 100 mA, a valueabove typical minimum holding and latching current thresholds, withresistor 251 and switch 250 sinking about 60 mA of current for a 1 Apeak current, and with the on time duration of the switch 250 (from theone shot circuit 252) being about 200 μs. Circuitry other than the oneshot circuit 252 having a fixed active time duration could besubstituted equivalently, such as by a variable or dynamic active timeunder the control of the controller 120, 120A, and those having skill inthe art may use numerous adaptive timing circuits to exercise such anoption.

FIG. 17 is a block and circuit diagram of an eighth representativeapparatus embodiment 100G and an eighth representative system embodiment105G in accordance with the teachings of the present disclosure. Theapparatus 100G implements both a full operation interface circuit 220(using adaptive interfaces 115D and 115F) and a combined start-upinterface and gradual or soft start power interface circuit 200, 210(using adaptive interface 115B, operating voltage bootstrap circuit 115Gwhich also functions as an adaptive interface), for example and withoutlimitation. In addition, through the use of the various sensors 125 andthe controller 120A (including the differentiator 261 for driving theone shot circuit 252), the apparatus 100G also implements a protectivemode interface circuit 230, as discussed in greater detail below. Theapparatus 100G is considered representative of any of the variouscombinations of a resonant process interface circuit 195 (implementedusing interface 115D), a full operation interface circuit 220, astart-up interface 200, a gradual or soft start power interface circuit210, and a protective mode interface circuit 230, and those having skillin the electronic arts will recognize innumerable equivalentcombinations which are considered within the scope of the presentdisclosure.

As illustrated, the apparatus 100G comprises a controller 120A, a memory160 (e.g., registers, RAM), a plurality of sensors 125, a plurality ofadaptive interface circuits 115, optional coupling inductor 270 andcapacitor 271, a bridge rectifier 110A, filter capacitor 235A, bootstrapcircuit 115G for fast generation of an operating voltage V_(CC) (inblock 290) (and bootstrap circuit 115G also serves to operate as anadaptive interface circuit 115B, as discussed below), a switching powersupply 130A (illustrated as having a transformer 280 in a flybackconfiguration), and an optional resistance 295 (which may also functionas a voltage or current sensor in representative embodiments). Theteachings of this disclosure do not limit the topology of the apparatus100G to the referenced flyback configuration, and any type or kind ofpower supply 130 configuration may be utilized, and may be implementedas known or becomes known in the electronic arts. The apparatus 100G iscoupled to a dimmer switch 75 and an AC line 35 via inductor 270 andcapacitor 271, which are then coupled to a bridge rectifier 110A, as anillustration of a representative rectifier 110 which is coupled throughother components to the dimmer switch 75. The adaptive interface 115Band adaptive interface 115D function as discussed above to provide thesubstantially matching electrical environments to the dimmer switch 75during start up, gradual or soft start, and full operational modes. Adimmer status sensor 125C is also illustrated, which may be implementedusing any type of sensor, such as using a voltage sensor 125A asdiscussed above. As illustrated, a plurality of sensors 125 areutilized, in addition to the dimmer status sensor 125C, namely, twocurrent sensors 125B₁, 125B₂, and voltage sensor 125A. The apparatus100G provides power to one or more LEDs 140, which may be an array ormultiple arrays of LEDs 140, of any type or color, with the apparatus100G and LEDs 140 forming system 105G.

Representative embodiments or other implementations for a controller120A and a memory 160 are described in greater detail below. The one ormore sensors are utilized to sense or measure a parameter, such as avoltage or current level, and may be implemented as known or becomesknown in the electronic arts. The switching power supply 130A and/or thecontroller 120A may and typically will receive feedback from the LEDs140 via sensors 125A, 125B₁, 125B₂, as illustrated.

The adaptive interface circuits 115 of the apparatus 100G function asdiscussed previously. Bootstrap circuit 115G may be used both togenerate an operational voltage during start up and to provideadditional current sinking capability during any of the states of thedimmer switch 75. Switching of transistor 285 is utilized for deliveringpower to the plurality of LEDs 140 via transformer 280.

The controller 120A implements a first control method comprising twoparts, a pulse width modulation (PWM) switching of the switching powersupply 130A (via transistor 285), using a variable duty cycle (“D”) upto a maximum duty cycle (“D_(MAX)”), followed by an additional operatingmode, referred to as a current pulse mode, to maintain stable operationof the dimmer switch 75 and provide the appropriate dimming of the lightoutput. The duty cycle D is determined by the controller 120 based on adetected input voltage level, so that the apparatus 100G and system 105Gmay accommodate a wide range of input voltages (which may vary from timeto time and also both nationally and internationally, e.g., from 90 to130 V).

The output power R_(OUT) delivered by the switching power supply 130A tothe LEDs 140 is equal to:

$P_{OUT} = \frac{\pi \; V^{2}D}{4{fL}_{m}}$

where V is the RMS input voltage;

-   -   D is the Duty cycle, averaged for a half cycle of the input AC        voltage;    -   f is the switching frequency of the power supply 130A; and    -   L_(m) is the magnetizing inductance of the transformer of the        switching power supply 130A.

For a constant switching frequency of the power supply 130A, the dutycycle D is inversely proportional to the square of the input voltage,i.e., when voltage is increasing the duty cycle drops to deliver thesame output power. Constant switching frequency is given for an exampleonly, and a method described below is transparent to the frequencydomain. Based on the output power, a maximum duty cycle D_(MAX) isoccurring at the minimum input voltage. As a switching power supply 130is generally designed with a predetermined or otherwise certain maximumduty cycle for a stable operation of its magnetic components, themaximum duty cycle D_(MAX) is predetermined or preselected at minimuminput voltage. When the output of the switching power supply 130 iscontrolled by a dimmer switch 75, the controller 120 is configured tohave an average duty cycle based on an average input voltage regulatedby the dimmer switch 75.

The following is an example to illustrate the insight of the presentdisclosure which introduces two separate control methodologies, withoutrelying solely on control through PWM as typically found in the priorart, in addition to independently controlling the amount of currentthrough the dimmer switch 75 to maintain stable operation. As anexample, at an input voltage of 90V RMS (Average 81 V), a D_(MAX)=0.6 isselected at a phase angle α=0. It should be noted that the maximumvolt-seconds (“voltsecs”) to magnetize the magnetic components 280 willhappen at the crest of the input voltage. In the event that the inputvoltage is or becomes 130 VRMs (average 120 V), the duty cycledeveloped, determined, or otherwise calculated by the controller 120decreases to D=0.29, and as for the same magnetizing voltsecs at thecrest of 130 V the duty cycle is D=0.415. As a consequence, working withD=0.415 is safe or otherwise appropriate for the magnetic components ofthe transformer 280. Assuming for this example that, at 130 V, the phasemodulation then introduced by the dimmer switch 75 is α=90°. The averageinput voltage will be 60V and controller 120 will generate a maximumpossible duty cycle D=D_(MAX)=0.6 to compensate for the lower inputvoltage. However, from the power supply 130A point of view, themagnetizing voltage at the crest still will be an amplitude of inputvoltage for which we calculated the maximum permissible duty cycle asD=0.415. The power supply 130A would then be forced to work at the crestwith an elevated duty cycle D=0.6 instead of D=0.415, which could meanthe saturation of the magnetic components 280 and power supply 130failure. Accordingly, recognizing that PWM alone will not accomplish thedesired stability under dimming conditions, to both draw sufficientcurrent for proper dimmer operation and provide the desired lightingoutput, the representative embodiments provide another, second controlmechanism for powering a switching power supply 130 from a dimmer switch75 for a stable interface of the dimmer switch 75 and switching powersupply 130.

A first control method is based on adjustment of the duty cycle based onaverage input voltage with maximum average duty cycle D_(MAX)preselected at minimum input voltage and stored in the controller 120A(or its memory or memory 160). For that predetermined or preselectedD_(MAX) value, another maximum parameter of the switching power supply130 is predetermined or otherwise preselected, namely, the maximumvolt-seconds (“VSEC_(MAX)”) at the crest or peak of the minimum inputvoltage and stored in the controller 120 (or its memory or memory 160).In accordance with various representative embodiments, the switchingpower supply 130A is enabled to operate using a range of input voltages,while the operational duty cycle is maintained below D_(MAX) and thesame operational volt-seconds are kept below maximum stored volt-secondsVSEC_(MAX). Accordingly, the switching power supply 130A operates with apotentially constant or adjustable duty cycle to generate a high powerfactor and it further switches to the volt-seconds limit whenever theduty cycle is excessive (i.e., within a predetermined range of D_(MAX))for the maximum preselected value of volt-seconds VSEC_(MAX).Implementation of this second inventive regulation mechanism of thefirst control method may be done by measuring input voltage andintegrating it (e.g., within the controller 120A, using an integrator,not separately illustrated) during the on time of the switch 285 of theswitching power supply 130A (and volt-seconds may also be obtainedthrough a feed forward technique, not shown on FIG. 17). It also can beimplemented by a switch current measurement, Ipeak control, using sensor125B₁ illustrated in FIG. 17. Rather than using a maximum volt-secondsVSEC_(MAX) parameter, another alternative control methodology for thesecond tier of this two-tiered control methodology will utilize a peakcurrent level (“I_(P)”) parameter, either the peak current level of theprimary inductor of transformer 280 or the output peak current level, toadjust the power provided to LEDs 140 under dimming conditions.

FIG. 18 is a flow diagram of a second representative method embodimentin accordance with the teachings of the present disclosure, and providesa useful explanation and summary of the two-tiered control methodology,using either the maximum volt-seconds VSEC_(MAX) parameter or the peakcurrent level (“I_(P)”) parameter. Beginning with start step 400, themethod determines an input voltage, step 405. Using the determined orsensed input voltage, the method determines a duty cycle D for pulsewidth modulation, step 410, which is less than (or equal to) the maximumduty cycle D_(MAX), to provide the selected or predetermined averageoutput current level, I_(AV). The switching power supply is thenswitched using the duty cycle D, step 415, providing the selected orpredetermined average output current level, I_(AV). The method thendetermines whether the duty cycle D is within a predetermined range of(or substantially equal to) the maximum duty cycle D_(MAX), step 420,and if so, transitions to current pulse mode (step 425), and if not, andthe method is to continue (step 430), iteratively returns to step 405,adjusting the duty cycle D as may be needed based on the sensed inputvoltage to provide the selected or predetermined average output currentlevel, I_(AV), and continuing to provide PWM for the switching powersupply 130, 130A. When the duty cycle D is within the predeterminedrange of (or substantially equal to) the maximum duty cycle D_(MAX),current pulse mode is implemented, step 425, providing a current pulsewith a dynamically adjustable or varying peak current I_(P) (either thepeak current level of the primary inductor of transformer 280 or theoutput peak current level), to increase the output current level duringa selected interval, up to a maximum peak current level (“I_(MAX)”), tomaintain the output current (usually the selected or predeterminedaverage output current level, I_(AV)) above a predetermined or selectedminimum level, to maintain sufficient current for the LEDs 140 to emitlight, and simultaneously allow a dimming effect. Alternatively, in step425, current pulse mode is also implemented, step 425, providing acurrent pulse with a dynamically adjustable or varying peak currentI_(P) (either the peak current level of the primary inductor oftransformer 280 or the output peak current level), to increase theoutput current level during a selected interval, up to a maximumvolt-seconds VSEC_(MAX) parameter, to maintain the output current(usually the selected or predetermined average output current level,I_(AV)) above a predetermined or selected minimum level, to maintainsufficient current for the LEDs 140 to emit light, and simultaneouslyallow a dimming effect. When the method is to continue, step 430, themethod returns to step 405 and iterates, and otherwise, the method mayend, return step 435.

The duty cycle control, peak current control, and/or maximumvolt-seconds VSEC_(MAX) control is implemented by the controller 120,120A, which may dynamically increase or decrease the duty cycle D tomaintain a selected or predetermined average output current (“I_(AV)”),up to the maximum duty cycle D_(MAX). Accordingly, if or when theapparatus 100 (and any of its variations 100A-100G) and system 105 (andany of its variations 105A-105G) is coupled to a dimmer switch 75 andthe user adjusts the dimmer switch to provide dimming, the duty cycle isdynamically adjusted and increased up to the maximum duty cycle D_(MAX),after which point the average output current to LEDs 140 may begin todecrease, and the output light emission is dimmed. The controller 120,120A, however, will transition to the additional, current pulse mode,and maintain the allowable peak current (amplitude) (i.e., up to apredetermined or selected maximum peak current or maximum volt-secondsVSEC_(MAX) parameter) to support sufficient current to the LEDs 140 suchthat light continues to be provided, and does not become so low that theLEDs 140 effectively shut off and stop emitting light. In these variousembodiments, a dimmer switch 75 is automatically accommodated, withoutany need for additional or separate detection of such a dimmer. Asignificant advantage of the first control method is that no additionalcurrent is utilized and, therefore, there are no additionalcorresponding power losses as found in the prior art.

The controller 120, 120A also functions as an adaptive interface(circuit 230) to implement the protective mode of operation. Using anyof the various sensors 125, the controller may determine that whilethere is incoming power from a dimmer switch 75 or other switch, forexample and without limitation, the output current (e.g., through theLEDs) is too high (e.g., indicative of a short circuit), or too low ornonexistent (indicative of an open circuit), or may detect other faultswithin any of the other various components. In these circumstances, thecontroller 120, 120A may provide a low power mode, taking sufficientpower to maintain an on-state of circuitry such as the controller 120,or may determine to shut down the apparatus 100, 100A-G, and/or theswitching power supply 130 completely.

FIG. 19 is a flow diagram of a third representative method embodiment inaccordance with the teachings of the present disclosure, by keeping thedimmer switch 75 operating stably but just at the edge or border ofpotentially becoming unstable, such as by having flicker or othertriggering issues. For example, and as illustrated above in FIGS. 6 and7, there are a wide variety of types of dimmer instability or improperperformance, such as (without limitation): (1) the dimmer switch 75 doesnot turn on within a half cycle of AC (35) being provided; (2) thedimmer switch 75 turns on more than one time within a half cycle of theAC (35); (3) following a zero crossing and conducting, a forward dimmerswitch 75 does not turn off at a next AC line voltage zero crossing; (4)a reverse dimmer switch 75 does not turn on following the first AC zerocrossing; (5) the phase angle α is changing from one half cycle toanother with different signs of changes, suggestive of the existence ofoscillations. Stable operation of a dimmer switch 75 may becharacterized using opposing criteria, such as (without limitation): (1)the dimmer switch 75 turns on once during each half cycle; (2) thedimmer switch 75 turns off (on) at AC zero crossings; and/or (3) thephase angle α is changing monotonically. Using any of the varioussensors 125, the controller 120 may be utilized to detect any of thesefeatures of improper or proper operation, such as using a voltage sensor125A to detect the voltage changes indicative of the dimmer switch 75turning on multiple times during a half cycle, or not turning off at theappropriate time, for example and without limitation.

Referring to FIG. 19, the method begins, start step 500, with the system105 being powered on, such as by applying AC voltage 35 to the dimmerswitch 75, and with adaptive interface circuits 115 set to their defaultlevels as discussed above, step 505, such that sufficient current levelsare drawn through the dimmer switch 75. Voltage or current levels aremonitored, step 510. When the voltage or current levels indicate thepresence of a dimmer switch, step 515, the method determines whether thedimmer switch is functioning properly or improperly, such as bydetecting the presence of flicker, step 520. For example, a dimmerswitch 75 may be present and also functioning properly, due to, forexample, the presence of other loads in parallel with the system 105,with sufficient current being drawn by all of the loads to maintainproper operation of the dimmer switch 75. Further, different dimmerswitches 75 may function improperly (or properly) at different holdingor latching currents, such that some dimmer switches 75 may functionproperly and others improperly for the same LEDs 140 and, therefore, itmay be necessary or desirable to detect flickering. Accordingly, whenthe method determines that the dimmer switch 75 is functioningimproperly in step 520, such as by detecting the presence of flicker,the method regulates the current from the dimmer switch 75 duringselected intervals, step 525, such as through control of any of thevarious adaptive interface circuits discussed above, and also asdiscussed below.

Another alternative may be utilized to diminish power consumption. Whenno dimmer switch 75 is present in step 515, or is functioning properlyin step 520, the controller 120 may be utilized to decrease the current(and power) drawn by the adaptive interface circuits 115 in theirdefault modes, determining whether any adaptive interface circuits 115with power dissipation are active, step 530. If so, and if the dimmerswitch 75 has not exhibited instability, an active adaptive interfacecircuit 115 may be selected, its current parameters stored in memory 160(and returned to if the dimmer switch 75 subsequently exhibitsinstability), and its power dissipation reduced, step 535, such as byreducing the amount of current through an adaptive interface circuit115B, with these parameters stored as next parameters in memory 160, forexample. The method then returns to step 205 and iterates, continuing tomonitor voltage and/or current levels and provide current regulationaccordingly. Following steps 525, 530, or 535, when the method is tocontinue (step 540), the method returns to step 510 and iterates,continuing to monitor voltage and/or current levels and provide currentregulation accordingly, and otherwise (such as when the system 105 isturned off) the method may end, return step 545.

For example, in this representative methodology, using dimmer statussensor 125C or a voltage sensor 125A, the representative apparatus 100Gdetects the presence of a dimmer switch 75. When a dimmer switch 75 isdetected, the controller 120 and one or more adaptive interface circuits(e.g., 115B and 115D or any other of the illustrated interface circuits)provide one or more of the following substantially matching electricalenvironments to the dimmer switch 75: (1) a small matching impedance tothe dimmer switch 75 triggering circuit, using adaptive interfacecircuit 115B controlled by controller 120; (2) supports greater thanholding current of the dimmer switch 75 when the bootstrap circuit 115Gis active and charging a V_(CC) capacitor 290, which thereby alsoconstitutes an adaptive interface circuit 115 controlled by controller120; (3) adjusts minimum power from the dimmer switch 75 at gradual orsoft start of the switching power supply 130, also using adaptiveinterface circuit 115B controlled by controller 120; (4) provides amatching small impedance to the dimmer switch 75 triggering circuit bykeeping the duty cycle D (of the switching power supply 130) close to 1,also under control of the controller 120; and/or (5) shaping the currentof the dimmer switch 75 in the resonant process, using one or more ofadaptive interface circuits 115D, 115E, 115F.

The controller 120, which may be embodied using one or a plurality ofcontrollers or other comparable circuits, is typically configured tocompare the sensed output voltage and current levels to correspondingpredetermined voltage and current values, which may be programmed andstored in memory 160, or which may be obtained from memory 160 (such asthrough a look up table) based upon other sensed values, such as sensedinput voltage levels. Following such comparisons, an error signal orerror level is determined, such as a difference between the sensed andpredetermined levels, and corresponding feedback provided, such as toincrease or decrease output voltage or current levels, in a first mode,through modulating the on-time (on-time pulse width) of the power switch285 at a selected switching frequency, or at a variable switchingfrequency, which is generally at a substantially higher frequency thanthe AC line frequency, and in a second mode, by modulating the peakcurrent levels.

Several novel features are implemented in the apparatus 100 (and any ofits variations 100A-100G), system 105 (and any of its variations105A-105G), and controller 120 embodiments. First, the adaptiveinterface circuits 115 independently enable operation with aphase-modulated dimmer switch 75, without unwanted flicker and prematurestart-up problems of the prior art. Second, the adaptive interfacecircuits 115 provide control based on a combination of both the state ofthe dimmer switch 75 and the state of the switching power supply 130.Third, a resonant mode is introduced with input current shaping orcontrol during dimmer switch 75 turn on. Fourth, a PWM control isimplemented, as a first part of a two-part control method, having adynamic and adjustable maximum duty cycle D_(MAX), based or dependent onthe (sensed) input voltage, having a theoretical dynamic range of 0° to180°, and accommodating a wide range of potentially varying inputvoltages. Fifth, a current pulse mode is implemented, as a second partof the two-part control method, having a variable and dynamicallyadjustable peak current level, for either the primary inductor peakcurrent level or the output peak current level, or up to a maximumvolt-seconds VSEC_(MAX) parameter.

Additional advantages of the representative embodiments are readilyapparent. The representative embodiments allow for solid state lighting,such as LEDs, to be utilized with the currently existing lightinginfrastructure and to be controlled by any of a variety of switches,such as phase-modulating dimmer switches, which would otherwise causesignificant operation problems. The representative embodiments furtherallow for sophisticated control of the output brightness or intensity ofsuch solid state lighting, and may be implemented using fewer andcomparatively lower-cost components. In addition, the representativeembodiments may be utilized for stand-alone solid state lightingsystems, or may be utilized in parallel with other types of existinglighting systems, such as incandescent lamps. The representativeembodiments essentially may work with any high impedance load and/oranything drawing comparatively low current through a dimmer switch.

The various methodologies described above may also be combined inadditional ways. For example, dimmer detection is not required, andinstead a series element may be programmed to switch at predeterminedintervals to accommodate a dimmer switch, or also as described abovewith reference to FIGS. 9 and 10, switching duty cycles may bedetermined from input parameters, such as sensed input voltage levels.In addition, when dimmer detection may be utilized, different strategiesare available, such as blocking current to prevent capacitors fromcharging, such as through a series current control element, or providingcurrent bypassing, such as through an adaptive current control element.

A wide variety of control methodologies and alternative adaptiveinterface circuits 115 have been illustrated to implement the proposedmethod of interfacing of a dimmer switch and switching power supply bymodulating dimmer current and further by shaping dimmer current in aresonant process. The present disclosure is to be considered as anexemplification of the principles of the invention and is not intendedto limit the invention to the specific embodiments illustrated. In thisrespect, it is to be understood that the invention is not limited in itsapplication to the details of construction and to the arrangements ofcomponents set forth above and below, illustrated in the drawings, or asdescribed in the examples. Methods and apparatuses consistent with thepresent invention are capable of other embodiments and of beingpracticed and carried out in various ways.

Although the invention has been described with respect to specificembodiments thereof, these embodiments are merely illustrative and notrestrictive of the invention. In the description herein, numerousspecific details are provided, such as examples of electroniccomponents, electronic and structural connections, materials, andstructural variations, to provide a thorough understanding ofembodiments of the present invention. One skilled in the relevant artwill recognize, however, that an embodiment of the invention can bepracticed without one or more of the specific details, or with otherapparatus, systems, assemblies, components, materials, parts, etc. Inother instances, well-known structures, materials, or operations are notspecifically shown or described in detail to avoid obscuring aspects ofembodiments of the present invention. In addition, the various figuresare not drawn to scale and should not be regarded as limiting.

Those having skill in the electronic arts will recognize that thevarious single-stage or two-stage converters may be implemented in awide variety of ways, in addition to those illustrated, such as flyback,buck, boost, and buck-boost, for example and without limitation, and maybe operated in any number of modes (discontinuous current mode,continuous current mode, and critical conduction mode).

Reference throughout this specification to “one embodiment,” “anembodiment,” or a specific “embodiment” means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present disclosure and notnecessarily in all embodiments, and further, are not necessarilyreferring to the same embodiment. Furthermore, the particular features,structures, or characteristics of any specific embodiment of thedisclosure may be combined in any suitable manner and in any suitablecombination with one or more other embodiments, including the use ofselected features without corresponding use of other features. Inaddition, many modifications may be made to adapt a particularapplication, situation, or material. It is to be understood that othervariations and modifications of the embodiments described andillustrated herein are possible in light of the teachings herein.

It will also be appreciated that one or more of the elements depicted inthe figures can also be implemented in a more separate or integratedmanner, or even removed or rendered inoperable in certain cases, as maybe useful in accordance with a particular application. Integrally formedcombinations of components are possible. In addition, use of the term“coupled” herein, including in its various forms such as “coupling” or“couplable,” means and includes any direct or indirect electrical,structural, or magnetic coupling, connection or attachment, oradaptation or capability for such a direct or indirect electrical,structural, or magnetic coupling, connection, or attachment, includingintegrally formed components and components which are coupled via orthrough another component.

As used herein for purposes of the present disclosure, the term “LED”and its plural form “LEDs” should be understood to include anyelectroluminescent diode or other type of carrier injection- orjunction-based system which is capable of generating radiation inresponse to an electrical signal, including without limitation, varioussemiconductor- or carbon-based structures which emit light in responseto a current or voltage, light-emitting polymers, organic LEDs, and soon, including within the visible spectrum, or other spectra such asultraviolet or infrared, of any bandwidth, or of any color or colortemperature.

A “controller” or “processor” may be any type of controller orprocessor, and may be embodied as one or more controllers, configured,designed, programmed, or otherwise adapted to perform the functionalitydiscussed herein. As the term controller or processor is used herein, acontroller or processor may include use of a single integrated circuit(“IC”), or may include use of a plurality of integrated circuits orother components connected, arranged, or grouped together, such ascontrollers, microprocessors, digital signal processors (“DSPs”),parallel processors, multiple core processors, custom ICs,application-specific integrated circuits (“ASICs”), field programmablegate arrays (“FPGAs”), adaptive computing ICs, associated memory (suchas RAM, DRAM and ROM), and other ICs and components. As a consequence,as used herein, the term controller (or processor) should be understoodto equivalently mean and include a single IC, or arrangement of customICs, ASICs, processors, microprocessors, controllers, FPGAs, adaptivecomputing ICs, or some other grouping of integrated circuits whichperform the functions discussed below, with associated memory, such asmicroprocessor memory or additional RAM, DRAM, SDRAM, SRAM, MRAM, ROM,FLASH, EPROM or E²PROM. A controller (or processor) (such as controller120), with its associated memory, may be adapted or configured (viaprogramming, FPGA interconnection, or hard-wiring) to perform themethodology, as discussed below. For example, the methodology may beprogrammed and stored, in a controller 120 with its associated memory(and/or memory 160) and other equivalent components, as a set of programinstructions or other code (or equivalent configuration or otherprogram) for subsequent execution when the processor is operative (i.e.,powered on and functioning). Equivalently, when the controller 120 isimplemented in whole or part as FPGAs, custom ICs and/or ASICs, theFPGAs, custom ICs or ASICs also may be designed, configured and/orhard-wired to implement described methodology. For example, thecontroller 120 may be implemented as an arrangement of controllers,microprocessors, DSPs and/or ASICs, collectively referred to as a“controller,” which are respectively programmed, designed, adapted, orconfigured to implement described methodology, in conjunction with amemory 160.

The memory 160, which may include a data repository (or database), maybe embodied in any number of forms, including within any computer orother machine-readable data storage medium, memory device, or otherstorage or communication device for storage or communication ofinformation, currently known or which becomes available in the future,including, but not limited to, a memory integrated circuit (“IC”), ormemory portion of an integrated circuit (such as the resident memorywithin a controller 120 or processor IC), whether volatile ornon-volatile, whether removable or non-removable, including withoutlimitation, RAM, FLASH, DRAM, SDRAM, SRAM, MRAM, FeRAM, ROM, EPROM, orE²PROM, or any other form of memory device, such as a magnetic harddrive, an optical drive, a magnetic disk or tape drive, a hard diskdrive, other machine-readable storage or memory media such as a floppydisk, a CDROM, a CD-RW, digital versatile disk (DVD) or other opticalmemory, or any other type of memory, storage medium, or data storageapparatus or circuit, which is known or which becomes known, dependingupon the selected embodiment. In addition, such computer-readable mediaincludes any form of communication media which embodiescomputer-readable instructions, data structures, program modules orother data in a data signal or modulated signal, such as anelectromagnetic or optical carrier wave or other transport mechanism,including any information delivery media, which may encode data or otherinformation in a signal, wired or wirelessly, including electromagnetic,optical, acoustic, RF or infrared signals, and so on. The memory 160 maybe adapted to store various look up tables, parameters, coefficients,other information and data, programs, or instructions, and other typesof tables such as database tables.

As indicated above, the controller 120 is programmed, using software anddata structures, for example, to perform described methodology.Technology described herein may be embodied as software which providessuch programming or other instructions, such as a set of instructionsand/or metadata embodied within a computer-readable medium, discussedabove. In addition, metadata may also be utilized to define the variousdata structures of a look up table or a database. Such software may bein the form of source or object code, by way of example and withoutlimitation. Source code further may be compiled into some form ofinstructions or object code (including assembly language instructions orconfiguration information). The software, source code, or metadata maybe embodied as any type of code, such as C, C++, SystemC, LISA, XML,Java, Brew, SQL and its variations (e.g., SQL 99 or proprietary versionsof SQL), DB2, Oracle, or any other type of programming language whichperforms the functionality discussed herein, including various hardwaredefinition or hardware modeling languages (e.g., Verilog, VHDL, RTL) andresulting database files (e.g., GDSII). As a consequence, a “construct,”“program construct,” “software construct,” or “software,” as usedequivalently herein, means and refers to any programming language, ofany kind, with any syntax or signatures, which provides or can beinterpreted to provide the associated functionality or methodologyspecified (when instantiated or loaded into a processor or computer andexecuted, including the controller 120, for example).

The software, metadata, or other source code and any resulting bit file(object code, database, or look up table) may be embodied within anytangible storage medium, such as any of the computer or othermachine-readable data storage media, as computer-readable instructions,data structures, program modules, or other data, such as discussed abovewith respect to the memory 160, e.g., a floppy disk, a CD-ROM, a CD-RW,a DVD, a magnetic hard drive, an optical drive, or any other type ofdata storage apparatus or medium, as mentioned above.

In the foregoing description and in the figures, sense resistors areshown in representative configurations and locations; however, thoseskilled in the art will recognize that other types and configurations ofsensors may also be used and that sensors may be placed in otherlocations. Alternate sensor configurations and placements are within thescope of the disclosure.

As used herein, the term “DC” denotes both fluctuating DC (such as isobtained from rectified AC) and constant voltage DC (such as is obtainedfrom a battery, voltage regulator, or power filtered with a capacitor).As used herein, the term “AC” denotes any form of alternating currentwith any waveform (sinusoidal, sine squared, rectified sinusoidal,square, rectangular, triangular, sawtooth, irregular, etc.) and with anyDC offset and may include any variation such as chopped or forward- orreverse-phase modulated alternating current, such as from a dimmerswitch.

With respect to sensors, we refer herein to parameters that “represent”a given metric or are “representative” of a given metric, where a metricis a measure of a state of at least part of the regulator or its inputsor outputs. A parameter is considered to represent a metric if it isrelated to the metric directly enough that regulating the parameter willsatisfactorily regulate the metric. For example, the metric of LEDcurrent may be represented by an inductor current because they aresimilar and because regulating an inductor current satisfactorilyregulates LED current. A parameter may be considered to be an acceptablerepresentation of a metric if it represents a multiple or fraction ofthe metric. It is to be noted that a parameter may physically be avoltage and yet still represent a current value. For example, thevoltage across a sense resistor “represents” current through theresistor.

In the foregoing description of illustrative embodiments and in attachedfigures where diodes are shown, it is to be understood that synchronousdiodes or synchronous rectifiers (for example, relays, MOSFETs, or othertransistors switched off and on by a control signal) or other types ofdiodes may be used in place of standard diodes within the scope of thepresent disclosure. Representative embodiments presented here generallygenerate a positive output voltage with respect to ground; however, theteachings of the present disclosure apply also to power converters thatgenerate a negative output voltage, where complementary topologies maybe constructed by reversing the polarity of semiconductors and otherpolarized components.

For convenience in notation and description, transformers such astransformer 280 are referred to as a “transformer,” although inillustrative embodiments, it behaves in many respects also as aninductor. Similarly, inductors can, under proper conditions, be replacedby transformers. We refer to transformers and inductors as “inductive”or “magnetic” elements, with the understanding that they perform similarfunctions and may be interchanged within the scope of the presentdisclosure.

Furthermore, any signal arrows in the drawings/figures should beconsidered only representative, and not limiting, unless otherwisespecifically noted. Combinations of components of steps will also beconsidered within the scope of the present disclosure. The disjunctiveterm “or,” as used herein and throughout the claims that follow, isgenerally intended to mean “and/or,” having both conjunctive anddisjunctive meanings (and is not confined to an “exclusive or” meaning),unless otherwise indicated. As used in the description herein andthroughout the claims that follow, “a,” “an,” and “the” include pluralreferences unless the context clearly dictates otherwise. Also, as usedin the description herein and throughout the claims that follow, themeaning of “in” includes “in” and “on” unless the context clearlydictates otherwise.

The foregoing description of illustrated embodiments of the presentinvention, including what is described in the summary or in theabstract, is not intended to be exhaustive or to limit the invention tothe precise forms disclosed herein. From the foregoing, it will beobserved that numerous variations, modifications, and substitutions areintended and may be effected without departing from the spirit and scopeof the disclosure. It is to be understood that no limitation withrespect to the specific methods and apparatus illustrated herein isintended or should be inferred. It is, of course, intended to cover bythe appended claims all such modifications as fall within the scope ofthe claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A system for powerconversion, the system couplable to a first switch coupled to analternating current (AC) power source, the system comprising: aswitching power supply including a second switch; solid state lightingcoupled to the switching power supply; a voltage sensor; a currentsensor; a memory; a first adaptive interface circuit including aresistive impedance, wherein the resistive impedance is configured toconduct current from the first switch in a default mode; a secondadaptive interface circuit configured to create a resonant process ifthe first switch is turned on; and a controller coupled to the voltagesensor, the current sensor, the memory, the second switch, the firstadaptive interface circuit, and the second adaptive interface circuit,wherein the controller is configured to modulate the second adaptiveinterface circuit to provide a current path during the resonant processif the first switch is turned on.
 2. The system of claim 1, wherein thefirst switch comprises a phase-modulated dimmer switch.
 3. The system ofclaim 1, wherein the controller is further configured to modulate acurrent of the first switch during the resonant process.
 4. The systemof claim 1, further comprising: a third adaptive interface circuitconfigured to modulate a current of the first switch during the resonantprocess.
 5. The system of claim 1, wherein the controller is furtherconfigured to use the first adaptive interface circuit to conductcurrent during a start-up state or a gradual start state.
 6. The systemof claim 5, wherein the controller is further configured to use thefirst adaptive interface circuit to conduct current during charging of atrigger capacitor of the first switch, during turn on of the firstswitch, and during conduction of the first switch.
 7. The system ofclaim 1, wherein the controller is further configured to switch thefirst adaptive interface circuit to provide a constant resistiveimpedance to the first switch.
 8. The system of claim 1, wherein thecontroller is further configured to modulate the first adaptiveinterface circuit to provide a variable resistive impedance to the firstswitch.
 9. The system of claim 1, wherein the controller is furtherconfigured to, in response to an operational voltage reaching apredetermined level, modulate the first adaptive interface circuit andtransition to a gradual start asynchronously to the state of the firstswitch.
 10. The system of claim 1, wherein the second adaptive interfacecircuit further comprises a resistive impedance, wherein the controlleris further configured to determine a peak input current level, andwherein the controller is further configured to switch the resistiveimpedance to create the current path in response to reaching the peakcurrent input level.
 11. The system of claim 1, wherein the secondadaptive interface circuit comprises a switched resistive impedance,wherein the controller is further configured to determine a peak inputcurrent level, and wherein the controller is further configured tomodulate the switched, resistive impedance to create the current path inresponse to reaching the peak input current level.
 12. The system ofclaim 1, wherein during a full power mode the controller is furtherconfigured to, if the trigger capacitor of the first switch is charged,operate the switching power supply at a one-hundred percent duty cycleor in a DC mode.
 13. The system of claim 1, wherein during a full powermode the controller is further configured to, if the first switch isturned on, operate the switching power supply at a substantially maximuminstantaneous power for a predetermined period of time.
 14. The systemof claim 1, wherein the second adaptive interface circuit furthercomprises an inductor in parallel with a resistor, and wherein during afull power mode the controller is further configured to, if the firstswitch is turned on, operate the switching power supply at asubstantially maximum instantaneous power until the inductor hassubstantially discharged.
 15. The system of claim 1, the controller isfurther configured to use the second adaptive interface circuit toconduct current during a full operational power state.
 16. The system ofclaim 1, the controller is further configured to adjust a minimum powerfrom the first switch during a gradual start phase.
 17. The system ofclaim 1, wherein the second adaptive interface circuit further comprisesa switchable resistive impedance, and wherein the controller is furtherconfigured to use the second adaptive interface circuit to provide acurrent path during a start-up phase of the switching power supply,during a gradual start up of the switching power supply, or during afull operational mode of the switching power supply.
 18. The system ofclaim 1, further comprising: an operational voltage bootstrap circuitcoupled to the switching power supply, wherein the operational voltagebootstrap circuit is configured to generate an operational voltage. 19.The system of claim 18, wherein the first adaptive interface circuitfurther comprises the operational voltage bootstrap circuit.
 20. Thesystem of claim 1, wherein the controller is further configured todetermine a maximum duty cycle corresponding to a sensed input voltagelevel, wherein the controller is further configured to provide a pulsewidth modulation operating mode using a switching duty cycle less thanthe maximum duty cycle, and wherein the controller is further configuredto provide a current pulse operating mode in response to the switchingduty cycle being within a predetermined range of the maximum duty cycle.21. The system of claim 20, wherein the controller is further configuredto determine or obtain from the memory a maximum duty cyclecorresponding to the sensed input voltage level.
 22. The system of claim20, wherein the controller is further configured to determine or varythe switching duty cycle to provide a predetermined or selected averageor peak output current level.
 23. The system of claim 20, wherein thecontroller is further configured to determine a peak output currentlevel up to a maximum voltseconds parameter.
 24. The system of claim 1,wherein the controller is further configured to detect a malfunction ofthe first switch.
 25. The system of claim 24, wherein the controller isfurther configured to detect the malfunction by determining at least twoinput voltage peaks or two input voltage zero crossings during ahalf-cycle of the AC power source.
 26. The system of claim 1, whereinthe first adaptive interface circuit further comprises: a firstresistor; a transistor coupled in series to the first resistor, whereina base or a gate of the transistor is coupled to the controller; and asecond resistor coupled to the base or the gate of the transistor. 27.The system of claim 1, wherein the first adaptive interface circuitfurther comprises: a first resistor; a transistor coupled in series tothe first resistor, wherein a base or a gate of the transistor iscoupled to the controller; a second resistor coupled to a source or anemitter of the transistor; and a diode coupled to the base or gate ofthe transistor and coupled to the second resistor.
 28. The system ofclaim 1, wherein the second adaptive interface circuit furthercomprises: an inductor; and a resistor coupled in parallel to theinductor.
 29. The system of claim 1, wherein the second adaptiveinterface circuit further comprises: an inductor; a first resistorcoupled to the inductor; and a transistor, wherein a base or a gate ofthe transistor is coupled to the first resistor.
 30. The system of claim29, wherein the second adaptive interface circuit further comprises: asecond resistor coupled to the inductor and coupled to a collector ordrain of the transistor; a first diode coupled to an emitter or sourceof the transistor; and a second diode coupled to the inductor and thefirst diode.
 31. The system of claim 1, wherein the second adaptiveinterface circuit further comprises: an inductor; a first resistor; adifferentiator; a one shot circuit coupled to an output of thedifferentiator; and a transistor coupled in series to the firstresistor, wherein a gate or base of the transistor is coupled to anoutput of the one shot circuit.
 32. The system of claim 1, wherein thesolid state lighting is one or more light-emitting diodes.
 33. Thesystem of claim 1, wherein the switching power supply comprises aflyback configuration.
 34. The system of claim 1, wherein the systemcomprises a form factor compatible with an A19 standard.
 35. The systemof claim 1, wherein the system is couplable through a rectifier to thefirst switch.
 36. The system of claim 1, wherein the system is couplablethrough a rectifier and an inductor to the first switch.
 37. Anapparatus for power conversion, the apparatus couplable to a firstswitch coupled to an alternating current (AC) power source, theapparatus further couplable to solid state lighting, the apparatuscomprising: a switching power supply including a second switch; avoltage sensor; a current sensor; a memory; a first adaptive interfacecircuit including a resistive impedance, wherein the first adaptiveinterface circuit is configured to conduct current from the first switchin a default mode; a second adaptive interface circuit configured tocreate a resonant process if the first switch is turned on; and acontroller coupled to the voltage sensor, the current sensor, thememory, the second switch, the first adaptive interface circuit, and thesecond adaptive interface circuit, wherein the controller is configuredto modulate the second adaptive interface circuit to provide a currentpath and to modulate a current of the first switch during the resonantprocess in response to the first switch being turned on.
 38. Theapparatus of claim 37, further comprising: a third adaptive interfacecircuit configured to modulate a current of the first switch during theresonant process.
 39. The apparatus of claim 37, wherein the controlleris further configured to use the first adaptive interface circuit toconduct current during a start-up state or a gradual start state. 40.The apparatus of claim 39, wherein the controller is further configuredto use the first adaptive interface circuit to conduct current duringcharging of a trigger capacitor of the first switch, during turn on ofthe first switch, and during conduction of the first switch.
 41. Theapparatus of claim 37, wherein the controller is further configured toswitch the first adaptive interface circuit to provide a constantresistive impedance to the first switch.
 42. The apparatus of claim 37,wherein the controller is further configured to modulate the firstadaptive interface circuit to provide a variable resistive impedance tothe first switch.
 43. The apparatus of claim 37, wherein the controlleris further configured to, in response to an operation voltage reaching apredetermined level, modulate the first adaptive interface circuit andtransition to a gradual start asynchronously to the state of the firstswitch.
 44. The apparatus of claim 37, wherein the second adaptiveinterface circuit comprises a resistive impedance, wherein thecontroller is further configured to determine a peak input currentlevel, and wherein the controller is further configured to switch theresistive impedance to create the current path in response to reachingthe peak input current level.
 45. The apparatus of claim 37, wherein thesecond adaptive interface circuit comprises a switched resistiveimpedance, wherein the controller is further configured to determine apeak input current level, and wherein the controller is furtherconfigured to modulate the switched, resistive impedance to create thecurrent path in response to reaching the peak input current level. 46.The apparatus of claim 37, wherein during a full power mode and duringcharging of a trigger capacitor of the first switch, the controller isfurther configured to operate the switching power supply at aone-hundred percent duty cycle or in a DC mode.
 47. The apparatus ofclaim 37, wherein during a full power mode the controller is furtherconfigured to, if the first switch is turned on, operate the switchingpower supply at a substantially maximum instantaneous power for apredetermined period of time.
 48. The apparatus of claim 37, wherein thesecond adaptive interface circuit comprises an inductor in parallel witha resistor, and wherein during a full power mode the controller isfurther configured to, if the first switch is turned on, operate theswitching power supply at a substantially maximum instantaneous poweruntil the inductor has substantially discharged.
 49. The apparatus ofclaim 37, wherein the controller is further configured to determine amaximum duty cycle corresponding to the sensed input voltage level,wherein the controller is further configured to provide a pulse widthmodulation operating mode using a switching duty cycle less than themaximum duty cycle, and wherein the controller is further configured toprovide a current pulse operating mode for the switching power supply inresponse to the duty cycle being within a predetermined range of themaximum duty cycle.
 50. The apparatus of claim 37, wherein thecontroller is further configured to detect a malfunction of the firstswitch by determining at least two input voltage peaks or two inputvoltage zero crossings during a half-cycle of the AC power source. 51.The apparatus of claim 37, wherein the second adaptive interface circuitfurther comprises: an inductor; and a resistor coupled in parallel tothe inductor.
 52. The apparatus of claim 37, wherein the second adaptiveinterface circuit further comprises: an inductor; a first resistorcoupled to the inductor; and a transistor including a base or a gatecoupled to the first resistor.
 53. The apparatus of claim 37, whereinthe second adaptive interface circuit further comprises: an inductor; afirst resistor; a differentiator; a one shot circuit coupled to anoutput of the differentiator; and a transistor coupled in series to thefirst resistor, wherein a gate or base of the transistor is coupled toan output of the one shot circuit.
 54. A system for power conversion,the system having a form factor compatible with an A19 standard, thesystem couplable to a dimmer switch coupled to an alternating current(AC) power source, the system comprising: a switching power supplyincluding a power switch; a light-emitting diode coupled to theswitching power supply; a voltage sensor configured to sense an inputvoltage level; a first adaptive interface circuit configured to conductcurrent from the dimmer switch in a default mode, wherein the firstadaptive interface circuit is further configured to provide asubstantially matching impedance to the dimmer switch; a second adaptiveinterface circuit configured to create a resonant process and to providea current path during the resonant process; a memory; and a controllercoupled to the voltage sensor, the memory, and the power switch, whereinthe controller is configured to provide a pulse width modulationoperating mode using a duty cycle less than a maximum duty cycle, andwherein the controller is configured to provide a current pulseoperating mode in response to the duty cycle being within apredetermined range of the maximum duty cycle.